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Solution: The greatest 5-digit number = 99999 The smallest 5-digit number = 10000 Their difference = 99999 – 10000 = 89999 Example 7: What number must be added to 84890 to get the largest 5-digit number? Solution: The largest 5-digit number is 99999. The number to be added to 84890 to get 99999 is 99999 – 84890 = 15109 Therefore, the number to be added is 15109. Drill Time Concept 4.1: Add and Subtract 5-digit Numbers 1) Add the following: a) 56249 + 12121 b) 42584 + 23568 c) 87216 + 11114 d) 65312 + 25842 e) 35216 + 42355 2) Subtract the following: a) 59423 – 12546 b) 86531 – 65372 c) 95361 – 46472 d) 11213 – 11206 e) 34536 – 15623 3) Word problems a) Tanu went to purchase a TV set from an electronics shop. The price of the TV was ` 25689. She paid to the shopkeeper ` 50000. How much money will she receive back? b) H arisharan collected 12568 beads for a design. Iru collected 25638 beads for the same design. How many beads did they collect in all? Addition and Subtraction 41

Chapter Multiplication 5 Let Us Learn About • multiplying 3-digit and 4-digit numbers. • p roperties of multiplication. • m ultiplying using standard and lattice algorithms. • multiplying mentally. Concept 5.1: Multiply 3-digit and 4-digit Numbers Think Jasleen went to the stadium to watch a rugby match with her parents. She observed that the seats are arranged in many rows and columns. All the seats were occupied. She wanted to guess the total number of people who watched the match that day. How will she be able to do that? Recall We have learnt to multiply 2-digit and 3-digit numbers by 1-digit and 2-digit numbers. 42

Let us solve the following to revise the concept of multiplication. TO H TO H TO H TO 39 256 589 875 ×2 ×3 ×4 ×5 & Remembering and Understanding Standard algorithm is the method of multiplication in which the product is regrouped as ones and tens. Let us now learn to multiply 3-digit numbers by 3-digit numbers and 4-digit numbers by 1-digit numbers using standard algorithm. Multiply a 3-digit number by a 3-digit number Multiplying a 3-digit number by a 3-digit number is similar to multiplying a 3-digit number by a 2-digit number. Let us see an example. Example 1: Multiply: 159 × 342 Solution: To multiply the given numbers, follow these steps. Steps Solved Solve these Step 1: Multiply the multiplicand by the ones of the Th H T O T Th Th H T O multiplier, that is, 159 × 2. 526 Regroup if necessary. 11 159 ×235 Step 2: Put a 0 below the ones ×342 place of the product obtained 318 in the above step. Multiply the multiplicand by the tens of the Th H T O multiplier, that is, 159 × 4. Regroup if necessary. 23 11 159 ×342 318 6360 Multiplication 43

Steps Solved Solve these Step 3: Put two 0s below the T Th Th H T O ones and the tens places of T Th Th H T O the product obtained in the 425 previous step. Multiply the 12 ×119 multiplicand by the hundreds of the multiplier, that is, 159 × 3. 23 T Th Th H T O Regroup if necessary. 301 11 Step 4: Add the products from 159 ×769 steps 1, 2 and 3. This sum gives ×342 the required product. 318 6360 4 7700 T Th Th H T O 12 23 11 159 ×342 318 + 6360 +4 7 7 0 0 54 378 Multiply a 4-digit number by a 1-digit number Multiplying a 4-digit number by a 1-digit number is similar to multiplying a 3-digit number by a 1-digit number. Let us see an example. Example 2: Multiply: 3628 × 7 Solution: T Th Th H T O 4 15 3 628 ×7 2 5 396 44

Th H T O Solve these Th H T O Th H T O 2568 1259 ×8 5689 ×4 ×2 Properties of Multiplication Identity Property: For any number ‘a’, a × 1 = 1 × a = a. 1 is called the multiplicative identity. For example, 461 × 1 = 1 × 461 = 461. Zero Property: For any number ‘a’, a × 0 = 0 × a = 0. For example, 568 × 0 = 0 × 568 = 0. Commutative Property: If ‘a’ and ‘b’ are any two numbers, then a × b = b × a. For example, 12 × 3 = 36 = 3 × 12. Associative Property: If ‘a’, ‘b’ and ‘c’ are any three numbers, then a × (b × c) = (a × b) × c. For example, 3 × (4 × 5) (3 × 4) × 5 3 × 20 12 × 5 60 60 (3 × 4) × 5 = 3 × (4 × 5) Distributive Property: 1) If 'a', 'b' and 'c' are any three numbers, then: a × (b + c) = (a × b) + (a × c). For example, 2 × (3 + 5) = (2 × 3) + (2 × 5). 2 × 8 = 6 + 10 16 = 16 Multiplication distributes over addition. Multiplication 45

2) If 'a', 'b' and 'c' are any three numbers then: a × (b − c) = (a × b) − (a × c). For example, 2 × (8 − 5) = (2 × 8) − (2 × 5). 2 × 3 = 16 − 10 6=6 Multiplication distributes over subtraction. Application Let us see a few real-life examples involving multiplication of 4-digit numbers. Example 3: Neena had 450 pencils in a box. There were 212 T Th Th H T O such boxes. How many pencils did Neena have 1 Solution: in all? 1 450 Number of pencils in a box = 450 ×212 Number of such boxes = 212 1900 + 4500 Total number of pencils = 450 × 212 Therefore, Neena had 95400 pencils. +9 0 0 0 0 9 5400 Example 4: 3542 students went to school from each town. There were 4 such towns. How many students went to school? Solution: Number of students who went to school from each town = 3542 Number of towns = 4 T Th Th H T O Total number of students who went to school 21 = 3542 × 4 Therefore, 14168 students went to school. 3542 ×4 1 4168 Higher Order Thinking Skills (H.O.T.S.) We know that the smallest 4-digit number is 1000 and the largest 4-digit number is 9999. Let us multiply the largest 4-digit number by the smallest and the largest 1-digit numbers. 46

Example 5: Multiply the largest 4-digit number by the smallest Th H T O 1-digit number. 9999 Solution: The largest 4-digit number = 9999 ×1 9999 The smallest 1-digit number = 1 We know that the product obtained when any number is multiplied by 1 is the Example 6: number itself. Solution: Therefore, 9999 × 1 = 9999. Multiply the largest 4-digit number by the largest T Th Th H T O 1-digit number. The largest 4-digit number = 9999 888 The largest 1-digit number = 9 9999 Therefore, 9999 × 9 = 89991. ×9 8 9991 Concept 5.2: Multiply Using Lattice Algorithm Think Jasleen knows how to multiply a 3-digit number by a 2-digit number. But she makes some mistakes. She wants a simple method for multiplication. Do you know any such method? Recall We know multiplication using standard algorithm. Let us recall the standard algorithm of multiplication by solving the following sum. H TO Th H T O Th H T O Th H T O 22 542 142 1243 ×6 ×4 ×8 ×2 Multiplication 47

& Remembering and Understanding There are two ways to multiply numbers: 1) Standard Algorithm 2) Lattice Algorithm Let us now learn to multiply 2-digit and 3-digit numbers using lattice algorithm. The important features of the lattice algorithm: • Setting up the lattice before we begin multiplying • Doing all the multiplications first, followed by additions • There is no carry over in the multiplication phase of the algorithm Let us use the lattice algorithm to multiply: 1) a 2-digit number by a 1-digit number and a 2-digit number 2) a 3-digit number by a 2-digit number Multiply a 2-digit number by a 1-digit number and a 2-digit number Multiplying a 2-digit number by a 1-digit number and a 2-digit number is similar to multiplying a 1-digit number by a 1-digit number. Let us see an example. Example 7: Multiply: a) 29 × 3 b) 43 × 52 Solution: Construct the lattice as shown. Steps Solved Solved Solve these a) 29 × 3 b) 43 × 52 3 2× Step 1: (a) N umber of rows = 4 Number of digits in the 2 multiplier. (b) N umber of columns = Number of digits in multiplicand. 48

Steps Solved × Solved × Solve these a) 29 × 3 b) 43 × 52 Step 2: Write the 5 2× multiplicand along the 29 43 top of the lattice and the 4 multiplier along the right, 3 5 6 one digit for each row or column. Draw diagonals 2 6 1× to divide each box into parts as shown. 2 9× 4 3× 4 4 Step 3: Multiply each digit 2 2015 5 of the multiplicand by 73 5 7× each digit of the multiplier. 2 Write the products in 3 the cells where the 2 9× 4 3 × 1 corresponding rows and 0 2 columns meet. 2 1 5 6 73 0 5 Step 4: If the product is a 2 single digit number, put 0 0 0 in the tens place. 8 6 (2 × 3 = 6) = 06 Step 5: Add the numbers 2 9× 4 3× 6 3× along the diagonals 2 from the right to find 02 73 1 3 the product. Regroup if 20 55 needed. Write the sum 06 3 from left to right. 87 10 0 2 28 6 Therefore, 29 × 3 = 087 3 6 = 87 Therefore, 43 × 52 = 2236. Multiply a 3-digit number by a 2-digit number Multiplying a 3-digit number by a 2-digit number is similar to multiplying a 2-digit number by a 2-digit number. Multiplication 49

Let us see an example. Example 8: Multiply: 168 × 48 Solution: Construct a lattice as shown such that: (a) Number of rows = Number of digits in the multiplier. (b) N umber of columns = Number of digits in multiplicand. Steps Solved 8 × Solve these × 168 × 48 17 2 Step 1: Write the multiplicand 16 4 4 along the top of the lattice. Write the multiplier along the right, one 8 2 digit for each row or column. Draw diagonals to divide each box into parts as shown. Step 2: Multiply each digit of the 1 6 8× 2 6 2× multiplicand by each digit of the multiplier. Write the products in 0 2 34 3 the cells where the corresponding 4 4 2 rows and columns meet. 8 8 Step 3: If the product is a single 1 6 8 × 1 7 1× digit number, put 0 in the tens 2 place. 0 3 4 3 4 4 2 1 4 8 0 6 3 4 2× 8 8 4 3 Step 4: Add the numbers along 1 6 8× 2 the diagonals to find the product and write the sum from left to 0 2 3 4 right. 4 2 8 4 0 4 6 8 0 4 28 6 8 4 01 Therefore, 168 × 48 = 8064. 50

Application Let us now see a few real-life examples involving multiplication of 3-digit numbers. Example 9: There are 345 students in each class. Pooja’s 34 5 × school has 12 such classes. How many 00 0 1 students are there in her school? 34 5 1 2 Solution: Number of students in each class = 345 00 0 Number of such classes in Pooja’s school = 12 4 6 8 Total number of students 1 40 = 345 × 12 = 4140 Therefore, there are 4140 students in Pooja’s school. Example 10: 42 people were sitting in a row of a stadium to enjoy a cricket match. How Solution: many people would be there in all if there were 35 such rows? Number of people sitting in one row = 42 42 × Number of rows = 35 10 3 1 26 5 Total number of people in 35 rows = 42 × 35 = 1470 2 1 40 0 Therefore, there are 1470 people in the stadium. Train My B7 rain 0 Higher Order Thinking Skills (H.O.T.S.) We know how to multiply numbers using lattice algorithm. Let us see if we can analyse and solve the following. Example 11: Find the missing numbers. 2 3? × 23___ × 4___= 9954 0 1 n2 8 4 08 2 0 0 1 94 6 ? 4 954 Multiplication 51

Solution: We can see that the box in the top right corner has the number 28. It is the product of 4 and ?. That is, 4 × ? = 28 4 × 7 = 28 So, 7 is the first unknown number. Similarly, the box in the bottom left corner has 04. It is the product of 2 and?. That is, 2 × ? = 04 2 × 2 = 04 So, the second unknown number is 2. So, the required numbers are 7 and 2 so that 237 × 42 = 9954. Concept 5.3: Mental Maths Techniques: Multiplication Think Jasleen’s rose garden has rose plants planted in 7 rows. There are 8 plants in each row. Jasleen wanted to find out the total number of rose plants in her garden. How can she find that mentally? Recall To learn how to complete multiplication facts by adding partial products mentally, we must memorise tables from 1 to 5 and 10. For example, we know that 6 × 5 = 30. As 6 = 4 + 2, we have (4 + 2) × 5 = (4 × 5) + (2 × 5) = 20 + 10 = 30. & Remembering and Understanding While multiplying two numbers mentally, we split the larger number into two parts. Let us now understand how to complete multiplication facts by adding the products mentally. Example 12: Find the answer by adding the products. 8×9 52

Solution: Steps Solved Solve this , 8×9 7×6 Step 1: Check by how much is the larger number more than 5. The larger number is 9, The larger number is and from 5, we count 6, 7, 8 and 9. So, 9 is 4 more and from 5, we count than 5. and . So, is more than 5. Step 2: Write the number as the 5 + 4 = 9 + = sum of 5 and the other number. Step 3: Multiply the numbers of 5 × 8 = 40 and 5× = the sum by the smaller number. 4 × 8 = 32 and Use memorised tables of 1 to 5 and 10 to solve mentally. × = Step 4: Add both the products 40 + 32 = 72 + = . from step 3 to get the final Therefore, 8 × 9 = 72. Therefore, 7 × 6 = answer. Example 13: Find the answer by adding the products: 14 × 6 Solution: Steps Solved Solve this 14 × 6 12 × 8 Step 1: Check by how much is The larger number is 14, The larger number is ____, the larger number more than 10. and from 10, we count and from 10 we count 11, 12, 13 and 14. So, 14 is and . So is 4 more than 10. more than 10. Step 2: Write the larger number 10 + 4 = 14 + = as the sum of 10 and the other number. Multiplication 53

Steps Solved Solve this 14 × 6 12 × 8 Step 3: Multiply the sum in the previous step by the smaller 10 × 6 = 60 and 10 × = number given, using memorised 4 × 6 = 24 and = tables of 1 to 5 and 10. × Step 4: Add both the products 60 + 24 = 84 + = . from step 3 mentally to get the Therefore, 14 × 6 = 84. Therefore, 12 × 8 = final answer. Application We have learnt some easy ways of completing multiplication facts by adding the products mentally. Let us now see some examples where we apply this concept. Example 14: Rohit works for 8 hours in a day. He works 6 days in a week. For how many hours does he work in a week? Solution: Number of hours Rohit works in a day = 8 Number of days he works in a week = 6 Total number of hours Rohit works in a week = 8 × 6 The larger number is 8, and it is 3 more than 5. As 8 = 5 + 3, 8 × 6 = (5 × 6) + (3 × 6) = 30 +18 = 48. Therefore, Rohit works for 48 hours in a week. Example 15: Jaya’s father bought 7 boxes of mangoes, with 12 mangoes in each box. How many mangoes did Jaya’s father buy in all? Solution: Number of boxes of mangoes Jaya's father bought = 7 Number of mangoes in each box = 12 Total number of mangoes = 12 × 7 The larger number is 12, and it is 2 more than 10. 54

So, 12 = 10 + 2. Hence, 12 × 7 = (10 × 7) + (2 × 7) = 70 + 14 = 84. Therefore, Jaya’s father bought 84 mangoes in all. Higher Order Thinking Skills (H.O.T.S.) Let us now see some more examples where we multiply larger numbers mentally. Example 16: Find the answer by adding the products: 17 × 7 Solution: Steps Solved Solve this , 17 × 7 19 × 9 Step 1: Check by how much is the larger number more The larger number is 17, The larger number is than 10. and from 10 we count 11, 12, 13, 14, 15, 16 and from 10 we count and 17. So, 17 is 7 more than10. ,,,, , , , , and . So, is more than 10. Step 2: Take the number Number from step 1 is 7, Number from step 1 is , from step 1 and check by and from 5, we count 6 how much it is more than 5. and 7. and from 5, we count ,, and . So, is more So, 7 is 2 more than 5. than 5. Step 3: Write the three 10 + 5 + 2 = 17 + + = numbers whose sum is the larger number. 10 × 7 = 70 10 × = 5 × 7 = 35 5× = Step 4: Multiply each 2 × 7 = 14 = number of the sum in × the previous step by the smaller given number. Use memorised tables of 1 to 5 and 10 to solve mentally. Multiplication 55

Steps Solved Solve this 17 × 7 19 × 9 Step 5: Add all the three products from step 4 to get 70 + 35 + 14 = 119 + + = the final answer. Therefore, 17 × 7 = 119. Therefore, 19 × 9 =. Drill Time Concept 5.1: Multiply 3-digit and 4-digit Numbers 1) Multiply a 3-digit number by a 3-digit number. a) 247 × 567 b) 509 × 121 c) 892 × 469 d) 731 × 691 2) Multiply a 4-digit number by a 1-digit number. a) 6741 × 4 b) 3456 × 8 c) 9258 × 9 d) 5555 × 5 3) Word problems a) P ranav makes 253 cotton bags in a day. How many bags will he be able to make in the year 2017? [Hint: 2017 is not a leap year] b) T anya bought sweaters as Christmas gifts for her 7 cousins. If one sweater costs ` 2734 , then how much money in all did she spend for the gifts? Concept 5.2: Multiply Using Lattice Algorithm 4) Multiply a 2-digit number by a 2-digit number. a) 24 × 32 b) 56 × 15 c) 13 × 39 d) 67 × 51 5) Multiply a 3-digit number by a 2-digit number. a) 158 × 17 b) 451 × 39 c) 651 × 67 d) 721 × 41 6) Word problems a) A movie theatre sold 127 tickets for a movie. Cost of one ticket was ` 85. How much money did the theatre owner earn from that movie? b) There are 47 students in Class 3. Answer sheets were given to each student for Maths exam. If one answer sheet has 15 pages, then how many total sheets of paper were used for the exam? 56

Concept 5.3: Mental Maths Techniques: Multiplication 7) Multiply the following: a) 9 × 7 b) 9 × 6 c) 11 × 7 d) 14 × 6 e) 13 × 8 8) Word problems a) T here are 14 players in a football team. If 8 teams are participating in the district level football tournament, then how many pairs of boots are needed for them? b) Megha eats 8 chappatis daily. How many chappatis does she eat in a week? Multiplication 57

Chapter Time 6 Let Us Learn About • reading and writing time. • the 12-hour and the 24-hour clock formats. • converting 12-hour clock to 24-hour clock format and vice versa. • the terms ‘duration’, ‘end time’ and ‘start time’. • problems involving estimation of time. Concept 6.1: Duration of Events Think Jasleen was going to school. When she started from home, the time shown by the clock was . Jasleen was easily able to read it as 8 o’clock. When she reached the school, the time shown by the school clock was Jasleen’s found it difficult to read the time from the clock. Can you tell what time it is? Recall There are 24 hours in a day. In a clock, the hour hand shows hours and completes one turn in 12 hours. 58

The minute hand shows minutes and takes one turn in one hour. We have learnt to read time to the nearest hour and minutes when the minute hand is on any one of the numbers on the clock. Let us recall the concept by writing the time for the clocks shown below: Read the time shown by the clocks given: a) b) c) d) & Remembering and Understanding Observe this clock. The long hand is called the minute hand. The short hand is called the hour hand. It has numbers from 1 to 12 on its face. Between 12 and 1, there are four lines. Between 1 and 2, there are four lines. They divide the space between two consecutive numbers into five equal parts. Each division between these consecutive numbers indicates a minute. Thus, these sixty divisions together make 60 minutes or 1 hour. Example 1: Let us read the time shown by these clocks. One is done for you. a) b) c) Time 59

a) T he hour hand has b) The hour hand has c) T he hour hand has crossed 10. crossed ____________. crossed ____________. The minute hand is on the The minute hand is on the The minute hand is on the third division after 2. So, the minutes is (2 × 5 + 3) = __________. ___________. 13 minutes. So, the minutes is ________. So, the minutes is ________. Therefore, the time shown is 10:13. The time is ________. The time is ________. We have learnt to read and write time in the 12-hour clock format. Now, let us learn to read time in the 24-hour clock format. In 12-hour clock format: • The hour hand of the clock goes around the clock face (dial) twice in 24 hours. • To identify morning or evening, we write a.m. or p.m. along with the time. In 24-hour clock format: • The time is expressed as a 4-digit number (hhmm) followed by ‘h’ to denote hours. 12-hour clock time 24-hour clock time Read as 4:20 a.m. 0420 h Four twenty hours 11:40 a.m. 1140 h Eleven forty hours 5:30 p.m. 1730 h Seventeen thirty hours 7:35 p.m. 1935 h Nineteen thirty-five hours • Here, the first two digits from the left tell us the hours and the next two digits tell us the minutes. • We do not write a.m. or p.m. • 12 o’clock at midnight is written as 0000 h. • 12 o’clock in the afternoon is written as 1200 h. The time before noon is written in the 12-hour format but without a.m. For example, 5:30 a.m. is written as 0530 hours. • The time post noon is written by adding 12 to the number of hours. • When the number of hours is more than 12, then the time indicates post noon. For example, 1730 h, 1815 h, 2210 h and so on. • When the hour hand is at 12 and the minutes are more than 00, the time is past noon and we write p.m. along with the number. For example, 1220 h = 12:20 p.m. (Here, we do not subtract 12 from hours.) 60

To convert the time in 24-hour clock to12-hour clock format, we subtract 12 from the number of hours and write p.m. after the difference. To convert time from 12-hour clock into 24-hour clock for the time after 12 noon, we add 12 to the number of hours and omit writing p.m. Do you know? • Railways/Airlines/Armed forces use the 24-hour clock to record time. • The 24-hour clock is used in digital watches. Example 2: Convert the given time to 12-hour clock format. a) 1320 h b) 0550 h c) 0915 h d) 2105 h e) 1800 h f) 1945 h g) 2355 h h) 0030 h Solution: The 12-hour clock format are given below. a) (13 – 12):20 = 1:20 p.m. b) 5:50 a.m. c) 9:15 a.m. d) (21 – 12): 05 = 9:05 p.m. e) (18 – 12):00 = 6 p.m. f) (19 – 12): 45 = 7:45 p.m. g) (23 – 12):55 = 11:55 p.m. h) (00 + 12):30 = 12:30 a.m. We have learnt how to read and show time, exact to minutes and hours. Let us now consider an example that involves finding the length of time between two given times. Example 3: The clocks given show the start time and end time of a Maths class in a school. How long was the Maths class? Solution: The start time is 9:00 and the end time is 9:45. So, the time between is the length of the Maths class = 9:45 – 9:00 = 45 minutes Time 61

The time between two given times is called the length of time or time duration or time interval. It is given by the difference of end time and start time. Application Let us see a real-life example involving duration of time. Example 4: Neha went to the airport to see off her uncle. There she saw the departure time for Flight 142 to Hyderabad as 1102 h. What was the time of departure of the flight in the 12-hour clock time? Solution: Time of departure of the flight = 1102 h 1102 h is in hhmm form. Since 11 < 12, the given time is a.m. Therefore, the given time in 12-hour clock is 11: 02 a.m. Higher Order Thinking Skills (H.O.T.S.) Let us now see a few more real-life examples involving the duration of time. Example 5: Anil took a flight from Delhi at 10:10 p.m. and reached Hyderabad in 2 hours 5 minutes. At what time did the flight reach Hyderabad? Solution: Start time of the flight = 10:10 p.m. Duration of travel = 2 hours 5 minutes End time = Start time + Duration = 10:10 p.m. + 2 hours 5 minutes = 12:15 a.m. (After 12 midnight, time is taken as a.m.) Therefore, Anil’s flight reached Hyderabad at 12:15 a.m. Example 6: A movie began at 5:35 p.m. Lucky switched on the TV at 6:23 p.m. For how much time did Lucky miss the movie? Solution: Start time of the movie = 5:35 p.m. Time at which Lucky switched on the TV = 6:23 p.m. 5:35 pm to 6 p.m. = 25 minutes 6 pm to 6:23 p.m. = 23 minutes 62

The time for which Lucky missed the movie = (25 + 23) = 48 minutes Therefore, Lucky missed the movie for 48 min. Example 7: When Shruti was having her breakfast, the clock showed 7:45. Express the time in the 12-hour and 24-hour clock formats? Solution: The time when Shruti was having her breakfast = 7:45 This time in the 12 hour clock time is 7:45 a.m. In the 24-hour clock time, it is 0745 h. Concept 6.2: Estimate Time Think Jasleen’s father was trying to book flight tickets from Mangalore to Dubai. He asked Jasleen to see the flight timings. He wanted her to find the time it would take for him to reach Dubai. Do you know how to find that? Recall The time from midnight 12 to midday 12 is 12 hours. The time from midday 12 to midnight 12 is 12 hours. Observe this timeline. 12 12 Mid Mid night night 12 hours Mid 12 hours Morning day Afternoon / Evening The time after midnight is written with a.m. after it. The time after midday is written with p.m. after it. So, 4 o’clock in the morning is 4 a.m., and 4 o’clock in the evening is 4 p.m. We can show the time in the morning or evening on a clock face. We know how to find the length of the time between two given times. Time 63

Now, let us compare the different units of time. • A minute is a shorter period of time than an hour. • An hour is shorter than a day. A day is shorter than a week. • A week is shorter than a month. • A month is shorter than a year. Express the following in a.m. or p.m. a) 3:30 in the morning b) 11:45 before noon c) 12:15 at midnight d) 5 in the evening & Remembering and Understanding We have learnt how to find the duration of time with the help of start time and end time. Duration = End time – Start time End time = Start time + Duration Start time = End time – Duration Let us understand this through a few examples. Example 8: If an event starts at 1:15 p.m. and it takes 2 hours to get over, then by what time will the event end? Solution: The start time of the event = 1:15 p.m. Duration of the event = 2 hours End time of the event = Start Time + Duration = 1:15 p.m. + 2 hours = 3:15 p.m. Therefore, the end time of the event is 3:15 p.m. Example 9: If a dance class ends at 9:20 a.m. and has taken 1 hour 15 minutes to complete, when did it begin? Solution: The end time of the dance class = 9:20 a.m. Duration of the class = 1 hour 15 minutes Start time of the class = End Time – Duration = 9:20 a.m. – 1 hour 15 minutes = 8:05 a.m. Therefore, the dance class began at 8:05 a.m. 64

Example 10: Ravi’s swimming class is for a duration of 1 h 50 min. If the class begins at 10:15 a.m., at what time does it end? Solution: Duration of Ravi’s swimming class = 1 h 15 min The start time of the class = 10:15 a.m. The end time of the class = 10:15 a.m. + 1 h 15 min = (10 + 1) h + (15 + 15) min = 11 h 30 min Therefore, Ravi’s swimming class ends at 11:30 a.m. Example 11: On the Sports day of a school, the indoor games competition begins at 11:40 a.m. If the competition goes on for 2 hours, at what time will it end? Solution: Start time of indoor games competition = 11:40 a.m. Duration of competition = 2 hours End time = Start time + Duration = 11:40 a.m. + 2 h = 1:40 p.m. Example 12: Our school’s annual day begins at 5:30 p.m. and would end after 5 h 12 min. At what time will it end? Express the end time in the 24-hour clock format. Solution: Start time of our annual day = 5:30 p.m. Duration of the celebration = 5 h 12 min End time = Start time + Duration = 5:30 p.m. + 5 h 12 min = 10:42 p.m. Therefore, the annual day ended at 10:42 p.m. In 24-hour clock time, it is (10 + 12) 42 h = 2242 h. Application Let us see a few real-life examples involving the estimation of time. Example 13: Radha participated in a drawing competition which was scheduled for one hour starting at 9 a.m. If Radha completes her drawing 15 minutes before the end time, at what time does she complete her drawing? Time 65

Solution: Drawing competition was for 1 hour, starting at 9 a.m. So, the competition was scheduled to end at 10 a.m. Radha completed her drawing 15 minutes before the end time. That is, she took (60 – 15) minutes that is 45 minutes for the drawing. 45 minutes from 9 a.m. is 9:45 a.m. Therefore, the time at which Radha completed her drawing was 9:45 a.m. Example 14: Leela goes for the music class at 4:48 p.m. and comes back at 6:45 p.m. How much time does she spend in the class? Solution: Start time of Leela’s music class is 4:48 p.m. End time of Leela’s music class is 6:45 p.m. 4:48 p.m. _1_2__m__in__u_te__s_ 5 p.m. ___1_h_o__u_r__ 6 p.m. 4__5_m__in__u_t_e_s 6:45 p.m. Time spent by Leela in the class = 1 hour + 45 minutes + 12 minutes = 1 hour 57 minutes Therefore, Leela spent 1 hour 57 minutes in the class. Higher Order Thinking Skills (H.O.T.S.) Let us consider another example that involves estimating time. Example 15: On 12th February, Raju saw the calendar and circled 21st March as his father’s birthday. He wanted to buy a gift for his father. How many days are left for him to buy the gift? Solution: Since it is not mentioned as a leap year, we assume the number of days in February to be 28. Days in February = 28 – 11 = 17 Days in March = 21 Total number of days = 17 + 21 = 38 Therefore, there are 38 days from 12th February to 21st March for Raju to buy a gift for his father. 66

Drill Time Concept 6.1: Duration of Events 1) Find the duration of time (in 24-hour clock) from the given start time and end time. a) Start Time = 12:00 and End Time = 02:15 b) Start Time = 15:00 and End Time = 19:00 c) Start Time = 3:15 and End Time = 7:20 d) Start Time = 7:20 and End Time = 10:41 e) Start Time = 5:56 and End Time = 7:57 2) Read the times on the clocks and write them in the 12-hour and 24-hour formats. a) b) Evening Afternoon c) d) Morning Afternoon Time 67

e) f) Evening Night 3) Word problems a) K arthik started his running race at 8:20 a.m. and finished it at 8:45 a.m. For how long did he run? b) S hirish was eating his dinner when it was 10:36 in the clock. What is the time in 12-hour and 24-hour clock formats? Concept 6.2: Estimate Time 4) Word problems a) If Sohail’s magic show begins at 5:56 p.m. and lasts for 2 hours, at what time does his show end? b) S unny’s karate class lasted for 4 hours. If it ended at 8:20 p.m., when did it begin? 68





EVS-I (SCIENCE) TERM 1

Preface IMAX partners with schools, supporting them with learning materials and processes that are all crafted to work together as an interconnected system to drive learning. IMAX presents the latest version of the Maple series – updated and revised after considering the perceptive feedback and comments shared by our experienced reviewers and users. Designed specifically for state board schools, the Maple series endeavours to be faithful to the spirit of the State Curriculum Framework and the National Curriculum Framework (NCF) 2005. Therefore, our books strive to ensure inclusiveness in terms of gender and diversity in representation, catering to the heterogeneous Indian classroom. The larger aim of the NCF 2005 regarding EVS-I teaching is to acknowledge and address the dynamic nature of EVS-I by focusing on the development of skills to acquire and process information scientifically. The Maple EVS-I textbooks and workbooks for state board schools offer the following features:  Interactive content that engages students through a range of open- ended questions that build curiosity and initiate scientific exploration  Opportunities for experimentation, analysis and synthesis of ideas and concepts  Exposure to locally relevant environmental problem solving  Effective use of visual elements to enable learning of structures, processes and phenomena  A focus on EVS-I specific vocabulary building  Integrated education of values and life skills  Promotion of participatory and contextualised learning through the engagement of all relevant stakeholders in the learning process Overall, the IMAX Maple EVS-I textbooks, workbooks and teacher companion books aim to enhance the development of scientific temper along with the inculcation of healthy habits, skills and values that promote environmentally sensitive and culturally responsive democratic citizenship among students. – The Authors

Textbook Features Let Us Learn About Think Contains the list of learning objectives to Introduces the concept/subtopic and be achieved in the lesson arouses curiosity among students Understanding Remembering • Explains the aspects in detail that form Introduces new concepts to build on the basis of the concept the prerequisite knowledge/skills required to understand and apply the objective • Includes elements to ensure that of the topic students are engaged throughout Application Amazing Facts Connects the concept to real-life Fascinating facts and trivia related to situations by enabling students to apply the concept what has been learnt through the practice questions Higher Order Thinking Skills (H.O.T.S.) Encourages students to extend the concept learnt to advanced application scenarios Inside the Lab Provides for hands-on experience with creating, designing and implementing something innovative and useful

Contents 4Class 1 Growing up with Family����������������������������������������������������������������������������������������������� 1 2 Digestive System���������������������������������������������������������������������������������������������������������� 5 3 Excretory System���������������������������������������������������������������������������������������������������������� 9 4 Diseases���������������������������������������������������������������������������������������������������������������������� 12 5 Keeping Our Neighbourhood Clean����������������������������������������������������������������������� 18 Inside the Lab – A������������������������������������������������������������������������������������������������������������� 23 Activity A1: Digestive System Activity A2: Disease Prevention Charades 6 Water Storage and Quality���������������������������������������������������������������������������������������� 25 7 Importance of Soil������������������������������������������������������������������������������������������������������ 31 8 Roots and Flowers������������������������������������������������������������������������������������������������������ 34

Lesson Growing up with Family 1 Let Us Learn About R young ones of animals and human babies. u taking care of babies. a adopting babies and animals into the family. h the roles of family members in caring for a baby. Think A stray dog in Reena’s neighbourhood gave birth to seven puppies. Reena and all her friends liked the cute puppies. Each of them decided to take a puppy home and take care of it. Have you or your friends ever done this? Remembering Do you like to play with kittens, chicks or puppies? They are the young ones of different animals. Where do you think they come from? Some animals lay eggs, and the young ones hatch out of them. The hen, fish, frog, snake and lizard are a few animals that lay eggs. Have you ever seen a bird coming out of its egg? 1

a hen and its eggs a chick coming out of an egg a snake and its eggs Some animals give birth to their babies. It means that the babies come out from their mothers’ bodies. Animals like the cat, cow, dog, horse, elephant and lion give birth to babies. Humans also give birth to babies. a dog with puppies a lion with a cub a mother with a baby A human baby grows inside its mother’s body for nine months before being born. Puppies and kittens grow inside their mothers’ bodies for about two months. Calves grow inside mother cows for about nine months. Understanding Young ones of animals mostly depend on their mother for food. Animals that lay eggs collect food and feed their babies. Have you ever seen how a baby bird is fed by its mother? Animals that give birth to young ones feed the babies on their milk. You might have seen calves, kittens or puppies drinking milk from their mothers’ body. a cow feeding its calf a bird feeding its young ones a cat feeding its kittens 2

Like animals, the human baby also depends on its mother for parents taking care food and protection. When a baby is born, the mother and of a baby father take care of their baby with the help of other family members. Babies need a lot of time and care from their an older brother spending time parents. Your parents have taken care of you since you were with a younger sibling a baby. Do you have a younger sibling? Do you like to spend some time with him or her? How do you take care of your sibling? Sometimes, if a mother spends more time with a baby to take care of it, an older child may feel left out. Do you know your mother and father were also born as small babies? Their parents too took care of them. Maybe, they went to school when they were small. They also had homework to do. They may have played with their friends and learnt new things. Their parents even scolded them for being naughty and doing something wrong! They may have fought with their siblings and cried. Ask your parents what they did when they were kids. babies grow up to become adults Application Sometimes, the young ones of animals lose their mother. Have you seen small puppies left alone without a mother to look after them? Sometimes some other animals may look after those young ones. Also, some people may bring them home and keep them as their pets. animals taking care of the young ones of other animals 3 Growing up with Family

Similarly, some children also may lose their parents. The children who have lost both their parents are called orphans. Some parents may take up the responsibility of such babies or children. Some families bring home a child of other parents as their own child. They make them part of their own family. This is called adoption. The parents who adopt them are called adoptive parents. They love and take care of their new child as their own. After adoption, the adopted child lives with his or her new parents in his or her new home. Suppose you have adopted a puppy. What all will you do to take of care it? How can you make sure that the puppy is well taken care of? Do you have any friends or relatives who have adopted young ones of any animals? Amazing Facts Did you know that the young ones of the cuckoo are taken care of by other birds? Cuckoos always lay their eggs in the nests of other birds. So, their young ones are fed and brought up by those birds. a bird feeding a cuckoo chick Higher Order Thinking Skills (H.O.T.S.) You have learnt about adoptive parents. Sometimes, people take up the responsibility of a child without adopting them. They are called foster parents. A foster parent may take up the responsibility of many children who were not born to them. Growing up with the care of parents and family is important for children. A child needs the care of all family members. Who takes care of you at home? Which family member spends more time with you? Generally, mothers spend more time to look after their babies. What are the things a father can do for a baby? Find out. 4

Lesson Digestive System 2 Let Us Learn About R digestion and the digestive system. u the process of digestion. a the importance of the digestive system. h hunger and famine. Think Your mother tells you to chew your food before swallowing it. Do you know why? chewing food Remembering activities we do We do a lot of work throughout the day. We need energy to work. From where do we get this energy? This energy comes from the food we eat. Food contains protein, fats carbohydrates, vitamins and minerals. Our body cannot absorb them directly. 5

Digestion means breaking down of food into smaller parts that can be absorbed into the bloodstream. The organ system in our body that helps in breaking down the food is called the digestive system. When the food is broken down, we get energy to do many things. Look at the picture of the digestive system. The different parts of the digestive system are: Mouth: We take food in our mouth. Digestion starts mouth food pipe here with the help of the teeth and tongue. liver stomach Food pipe: It is a long tube that connects the mouth with the stomach. Stomach: It is a stretchy bag-like organ. When the small large stomach is empty, it is about the size of a tennis intestine intestine ball. After a big meal, it expands to almost to the size of a football. anus Liver: It is the largest and heaviest organ inside the the human digestive system body. It is reddish brown. Small intestine: It is a long, narrow tube. It is twenty- two feet long. Large intestine: The large intestine is also like a tube. It is five feet long. It is called the large intestine because it is wider than the small intestine. Anus: It is the opening at the end of the digestive system. What happens to the food after we eat it? Let us find out. Understanding Digestion starts in the mouth. We chew the food with our teeth. digestion starts in mouth We have different types of teeth to chew the food and break it into pieces. The sharp teeth in the front help us to bite and cut the food into smaller pieces. The back teeth are flat and help to grind the food into a paste. Saliva mixes with the food. Saliva is produced inside our mouth. It mixes with the food and makes the food soft and wet. Teeth can now easily break down this wet food into smaller pieces. 6

The tongue helps in mixing the food with the saliva. It also pushes the chewed food towards the food pipe. The food pipe moves the food from the back of our throat to our stomach. Stomach walls make squeezing and relaxing movements. These movements help to mix the food with the stomach juices. The stomach juices help to break down the food. From the stomach, the food goes into the small intestine. The liver produces bile juice. It helps in the digestion of food. In the small intestine, the bile juice mixes with the food and breaks stomach movement it down further. The walls of the small intestine absorb all the useful parts of the food. Digestion of food gets completed in the small intestine. The remaining undigested material is pushed to the large intestine. When the food passes through the large intestine, water and some minerals get absorbed by the walls of the large intestine. Then it pushes the remaining waste matter into the anus. Anus pushes the undigested food waste out of the body. Application We get energy from the food we eat. So it is important to: • eat healthy food • take care of different organs of the digestive system What will happen if we do not eat food? If we do not eat food, the body will not get the nutrients and energy it needs to work. So, we will feel tired quickly. If we do not eat for very long periods of time, our body will become thin and weak. Due to the lack of nutrients, we may also become sick. What will happen, if our digestive system does not work? The food we eat will not get broken down. We will have indigestion. Indigestion may cause stomach pain, vomiting and so on. It is essential to take care of our mouth. It helps in digestion and tasting food. So, for a healthy digestive system, we must keep our mouth, tongue and teeth clean. Amazing Facts Do you know that the mouth produces about 1.7 litres of saliva every day? This amount is almost the same as that of a big bottle of Coca-Cola. Salivary glands in our mouth produce saliva. Digestive System 7

Higher Order Thinking Skills (H.O.T.S.) Why do we feel hungry after every few hours? Our body needs constant energy and nutrient supply to work. Once the food we eat gets digested and the nutrients are absorbed, we feel hungry. Hunger is the weakness caused by lack of food accompanied by a feeling to eat. It makes us tired. Have you ever felt hungry and did not get anything to eat for some time? Many people in the world do not get enough food to eat. They remain hungry. Imagine how difficult their life must be! Sometimes, in some places, there will be a widespread shortage of food. This shortage of food is called famine. During a famine, many people may die due to lack of food. 8

Lesson Excretory System 3 Let Us Learn About R excretion and the excretory system. U the process of excretion. A the importance of the excretory system. H kidney stones. Think We drink a lot of water throughout the day. There is some water in the food we eat too. What happens to all this water we take in? Remembering We have learnt earlier that our body gets the energy to work from the food we eat and the liquids we drink. The blood in our body absorbs the useful parts from the food and liquids that we take in. The unused food and water become waste. Leftovers from food are solid waste. Leftovers from the water and other liquids we drink are the liquid waste. Various processes taking place inside our body also produce waste. Removal of waste from the body is called excretion. We get rid of the waste from the air that we have taken in by breathing it out. We get rid of solid waste by pooping and liquid waste by peeing and sweating. 9

We have learnt that the digestive system gets rid of most of the solid wastes from our body. The organ system which removes the liquid waste from our body is called the excretory system. Look at the diagram of the excretory system. It includes the following organs of the excretory system: 1) A pair of kidneys: They are two bean-shaped structures kidney located near our stomach, one on each side of our ureter backbone. They are about the size of our fist. bladder 2) A pair of ureters: They are pipe-like structures. One ureter is attached to each kidney. 3) Urinary bladder: It is a bag-like structure that expands urethra as it fills with urine. It is balloon-shaped when filled. the human excretory system 4) Urethra: It is a pipe-like structure at the end of the bladder. It opens outside the body. Understanding Now let us learn how different excretory organs help in excretion. As the blood travels throughout the body, it collects more and more waste. The kidneys work like a filter. When the blood enters the kidneys, they filter the blood which passes through them. It takes about 45 minutes for the kidney to purify (clean) all the blood in our body. Kidneys work throughout the day. Kidneys send all the waste to the bladder through the ureters in the form of urine (commonly known as pee). The urinary bladder stores this urine. When the bladder is almost half full, we feel like peeing. During peeing (urinating), the urine from the bladder is thrown out through the urethra. In this way, liquid waste is removed from the blood and thrown out of our body as urine. Organs like the skin and lungs are also involved in removing excess water and salts from the body. Let us see how this happens. 1) Excretion through the skin: Skin is the largest excretory organ in our body. The liquid waste from our body is thrown out in the form of sweat. It is made up of extra water and salts from our body. It cools our body. sweating 10

2) Excretion through lungs: We breathe in and out with the help of breathing our lungs. During breathing, the lungs absorb the oxygen from the air we breathe. At the same time, carbon dioxide is thrown out of the body from the lungs as a waste. Application The excretory system removes waste from the body. If it does not work properly, the liquid wastes collect inside the body. This may lead to swelling of the body, especially on the legs, hands and face. If our kidneys don’t work properly, the colour and smell of the urine may change. We may feel tired, or we may start vomiting. How do we take care of the excretory organs? Have you heard of any fruit or vegetable that helps to keep our kidneys healthy? Find out more about such food items which can improve the working of our excretory system. Our skin and lungs also perform excretion. We should take care of them too. We should bathe regularly to take care of our skin. We should keep it clean using soap and water. We must do breathing exercises to keep the lungs healthy. We must protect our lungs from dust and smoke by wearing a mask when we go outside. Amazing Facts Most humans pee about 3000 times in a year. On an average, we take 21 seconds to pee. That is about 18 hours a year! Higher Order Thinking Skills (H.O.T.S.) Have you heard about kidney stones? They are the solid pieces of salt or minerals formed inside the kidneys. They vary in size. When they are small in size, like a grain of salt or sugar, they do not cause any problem. They come out of the body along with the urine. But when they are of the size of a pea, they block the ureter. This causes pain. How do kidney stones develop in kidneys? Kidney stones are formed due to excess salts and minerals in the urine. This may happen if we do not drink enough water. So, we should drink plenty of water to avoid the formation of kidney stones. kidney stones Excretory System 11

Lesson Diseases 4 Let Us Learn About R diseases and prevention. u types of diseases. a the prevention of various types of diseases. h epidemics. Think Vinay’s father woke up one morning with his nose red. His eyes were swollen. The doctor gave him medicines. He became healthy in a week. What do you think had happened to Vinay’s father? Remembering A disease is an unhealthy thing happening to the body or mind. There are many diseases that affect humans. For example, common cold, chickenpox, malaria, asthma, diabetes and many more. When we are unwell, our body shows some external signs that something is wrong. The signs could be a headache, stomach pain, runny nose, fever, cough, shivering and vomiting. These signs are called symptoms. They help the doctor identify why we have ill health. This method of identifying a disease from its signs and symptoms is called a diagnosis. 12

The best way to protect our body from diseases is to keep disease-causing germs away from our body. This is called the prevention of disease. Understanding Some diseases can spread from one person to another. Some diseases are not able to spread from one person to another. Let us learn about them. DISEASES that spread Some diseases spread from one person to another. These are caused by disease-causing germs. Germs are very tiny. They live all around us; in the air, water, food and so on. They are not visible to the human eye. Most of the germs are not harmful, but some cause diseases. Germs attack our body when it is weak. The germs spread in different ways. They can spread through touching, eating, drinking and breathing. Based on the way they spread, diseases are of different types: 1) Diseases that spread through the air are called airborne diseases. Germs from unhealthy people spread through the air when they cough or sneeze. When other people breathe in the same air, these germs may enter their body through the mouth or nose. They can cause diseases like common cold, chickenpox and measles. 2) Diseases that spread through water are called waterborne diseases. For example, typhoid, dysentery and cholera. 3) Some diseases spread through touch. Germs from diseased people may stick to things they touch and to clothes they wear. Touching those things, then touching your eyes, nose, mouth, or a cut on the body may allow germs to enter the body. 4) Some diseases are spread by insects like mosquitoes and houseflies. For example, malaria, dengue and chikungunya. DISEASES that do not spread Some diseases are not caused by germs. These diseases do not spread from one person to another. Let us discuss some of the causes of such diseases: 1) The body needs nutrients like vitamins, minerals and proteins. If the body does not get all these through the food we eat, we become ill. Vitamins are of different types like A, B, C, D, E and K. Important minerals needed for our body are calcium, iron, phosphorus and so on. Diseases 13

Disease caused Due to lack of night blindness scurvy vitamin A beriberi, pellagra vitamin C anaemia vitamin B goitre iron iodine 2) Sometimes, our internal organ systems do not work properly due to different reasons. This can cause diseases. Example: liver disease and heart failure 3) Harmful substances in food, water and air can also cause diseases. Example: allergies 4) Extreme hot or cold weather can also cause some diseases or allergies. Example: heatstroke and frostbites 5) Some diseases are passed on to children from their parents at the time of birth. Example: haemophilia Application Every time you come back from the washing hands with soap playground, your mother asks you to wash your hands and legs. Why is this so important? There is a famous saying: “Prevention is better than cure.” The best way to protect our body from diseases is to prevent the disease-causing germs from entering our body. The easiest way to do that is to keep our hands and legs clean by washing them with soap. Let us now learn some more ways to protect ourselves from diseases: PREVENTION OF DISEASES that spread There are different ways of preventing the diseases that spread from one person to another. 14

1) Prevention of airborne diseases • Use a handkerchief while sneezing or coughing. • Wear a mask in crowded places. • Do not spit here and there. • Keep the doors and windows of the house open during mornings and evenings. This allows sunlight to come into the house. Sunlight can kill disease-causing germs. • Vaccinations are preventive medicines. They protect us from wearing masks many airborne diseases. Example: tuberculosis and measles 2) Prevention of diseases that spread through touch • Wash both hands with soap and water before and after eating. This will also prevent diseases spread by touch. • Wash both hands and legs with soap and water after using the toilet. This will also prevent diseases spread by touch. 3) Prevention of waterborne diseases • Avoid having sherbet, cold water, ice, water purifier polio vaccination ice cream and so on from the roadside shops. • W e must drink clean water. Boiling water for 15–20 minutes kills most germs and makes it safe for drinking. These days we use water purifier or RO for purifying water. • V accination protects us from waterborne diseases. Example: polio, typhoid and hepatitis vaccines 4) Prevention of diseases spread by insects • M osquitoes spread many harmful diseases like malaria, dengue and so on. Wearing full-sleeved clothes and full pants may prevent mosquito bites. Applying a mosquito repellent cream or lotion when you go out to play is important. Sleeping under a mosquito net is also a way to prevent mosquito bites. Mosquitoes lay eggs in stagnant water. We must ensure that there is no stagnant water in and around our neighbourhood. mosquito net Diseases 15

• Houseflies cause diseases like typhoid and cholera. They carry germs from dirty places, dustbins and so on. They lay eggs in moist, dark and dirty areas. So, we should keep our houses and surroundings clean and moisture free. Also, we should keep food items in closed vessels to prevent flies sitting on them. Have you seen a housefly rubbing its legs? Find out why it does so. PREVENTION OF DISEASES that do not spread To avoid diseases that do not spread, we should eat a balanced diet with all the nutrients in the required amounts. We should try to avoid eating junk food. We should eat freshly prepared food, milk and fruits. We should also exercise and play outdoor games. People who live in cities should wear special masks when they go outdoors to protect themselves from the dust and smoke in the air. Most importantly, we should stay relaxed and happy. healthy food Being worried about anything or being angry makes our body weak, which can make us sick easily. In spite of taking all the care, if we suffer from any disease, we should go to the doctor. The doctor diagnoses the disease and gives medicines to treat it. exercising a doctor checking a patient Amazing Facts We have a system inside our body which protects us against disease-causing germs. When the germs enter our body, this system attacks and kills those germs. It is like an army of soldiers that protects us from our enemies! 16