Gap Closing. Representing and Comparing Decimals. Junior / Intermediate Student Book

Transcription

1 Gap Closing Representing and Comparing Decimals Junior / Intermediate Student Book

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3 Module 7 Representing and Comparing Decimals Diagnostic...4 Representing Decimal Tenths...7 Representing Decimal Hundredths...10 Counting by Tenths or Hundredths...14 Renaming Decimal Tenths...17 Comparing Decimal Tenths or Hundredths...21 Comparing Mixed Decimals...29 Templates Fraction Circles and Ten Frames...34 Place Value Chart (1)...35 Place Value Chart (2)...36 Place Value Chart (3) Grid (1) Grids (2) Grids...40 Number Lines...41

4 Diagnostic 1. Write each number in standard form (e.g., like 1.2 or 034). a) three hundredths b) twelve hundredths c) forty seven hundredths d) eight tenths e) four and eight tenths 2. Continue the count for three more terms: a) 1.8, 1.9,,, b) 2.37, 2.38,,, c) 0.97, 0.98,,, d) 1.07, 1.08,,, 3. Match the number to how you would say it. a) 1.3 one and three tenths b) 1.03 thirteen hundredths c) 1.30 one and thirty hundredths d) 0.13 one and three hundredths 4. Match the number to its equivalent (equal) form ones + 2 hundredths tenths + 2 hundredths ones + 4 hundredths hundredths 5. Tell how the 3 in 0.32 is different from the 3 in Marian Small, 2010 Representing and Comparing Decimals

5 Diagnostic 6. The full grid represents 1 whole. Write the decimal for how much is shaded. a) b) c) d) 7. Suppose the flat represents 1 whole. What is each amount worth? a) b) c) d) 8. Write a number to match the description: a) 3 in the hundredths place b) 7 in the tenths place 5 Marian Small, 2010 Representing and Comparing Decimals

6 Diagnostic 9. Complete to make the statement true. a) 0.3 is 3 tenths. It is also hundredths. b) 2 is tenths. It is also hundredths. c) 1.3 is 1 one and 3 tenths. It is also tenths. It is also hundredths. 10. Match the decimal to the words that best describe it. a) of something b) 0.25 most of something c) 0.32 about d) of something of something 11. a) To which whole number is 4.2 closest? b) To which whole number is 1.89 closest? c) To which amount of tenths is 1.89 closest? d) To which amount of tenths is 3.53 closest? 12. Put the numbers in order from least to greatest a) 1, 0.01, 0.1, 10, 100,,,, b) 0.36, 0.63, 0.03, 0.60, 0.81,,,, c) 0.49, 0.7, 0.36, 0.2, 0.11,,,, d) 4.2, 2.4, 3.6, 2.8, 1.12,,,, e) 12.1, 1.21, 0.12, 1.12, 2.1,,,, f) 1.03, 3.01, 0.13, 3.13, 3.31,,,, e) 12.3, 1.23, 3.21, 13.2, 13.21,,,, 13. Shade the grid to show why 0.3 and 0.30 are the same. 6 Marian Small, 2010 Representing and Comparing Decimals

7 Representing Decimal Tenths Learning Goal using the patterns of the place value system to represent tenths. Open Question 1. Draw pictures to show how 0.1, 1.1 and 2.1 are alike and how they are different. Explain how your pictures show how they are alike and how they are different. 2. Draw pictures to show how 0.1 and 0.9 are alike and how they are different. Explain how your pictures show how they are alike and how they are different. 7 Marian Small, 2010 Representing and Comparing Decimals

8 Representing Decimal Tenths Think Sheet The fraction 1 can also be written as the decimal In the place value system, 10 counters in the tenths column can be traded for one counter in the column to its left, the ones column. This makes sense since 10 tenths = 10 = Tens Ones Tenths 10_ 10 = 1 Notice that: the column to the right of the ones is called tenths, not tens. the tens is one column to the left of the ones and the tenths is one column to the right of the ones. a decimal point is used to separate the ones from the tenths. A number like 1.3 means 1 whole + 3 tenths. We read it as 1 and three tenths, saying the and for the decimal point. 1.3 is close to 1. A number like 1.7 means 1 whole + 7 tenths. It is closer to 2 than to 1. A decimal less than 1 is always written with a 0 in the ones place; for example, 0.4 means 0 wholes + 4 tenths of a whole. 1. Write two decimals for each picture one to tell the part that is shaded and one to tell the part that is not shaded. a) b) c) d) 8 Marian Small, 2010 Representing and Comparing Decimals

9 Representing Decimal Tenths 2. Write each as a decimal: a) 6 10 c) 1 b) d) Write each as a decimal: a) four and three tenths b) five and six tenths c) eight tenths d) ten and nine tenths e) ten tenths 4. What words would you use to say each of these? a) 3.1 b) 0.7 c) 2.8 d) To which whole number is each closest? a) 3.9 b) 5.2 c) You can use the words two, one, four, hundreds, and tenths (and other words, too) to write a number that includes a decimal part. a) List some of the numbers you could write. b) Tell how you would read each number. 9 Marian Small, 2010 Representing and Comparing Decimals

10 Representing Decimal Hundredths Learning Goal using the patterns of the place value system to represent hundredths. Open Question 1 centimetre is We write this as 0.01 m. of a metre since there are 100 cm in 1 m. 0 cm Choose 6 different centimetre lengths. Write each as metres, using a decimal. Make sure that: one length is not much more than 10 cm another length is very close to 1 m another length is about 1 of a metre long 2 another length is more than 3 m long. Choose two other lengths. Use phrases like the ones above to describe them. 10 Marian Small, 2010 Representing and Comparing Decimals

11 Representing Decimal Hundredths Think Sheet The fraction can be written as a decimal It represents one square on this grid. The fraction = 1 10 squares on the grid fills one column. Since there are 10 columns, that s 1 of the grid In the place value system, 10 counters in the hundredths column can be traded for one counter in the column to its left, the tenths column. 100 counters in the hundredths column can be traded for one counter two columns to the left. This makes sense since = 1. Tens Ones Tenths Hundredths Notice: the column to the right of the tenths is called hundredths, not hundreds. the hundreds column is two columns to the left of the ones and the hundredths column is two columns to the right of the ones. a decimal point is used to separate the ones from the tenths means 1 whole + 3 hundredths. It is close to means 1 whole + 87 hundredths. It is also 1 whole and 8 tenths and 7 hundredths. It is closer to 1.9 than to 1.8. It is closer to 2 than to 1. A decimal less than 1 is always written with a 0 in the ones place. For example, 0.74 mean 0 wholes + 74 hundredths of a whole. 11 Marian Small, 2010 Representing and Comparing Decimals

12 Representing Decimal Hundredths 1. Write two decimals for each picture one to tell the part that is shaded and one to tell the part that is not shaded. a) (shaded) b) (shaded) (unshaded) (unshaded) c) (shaded) d) (shaded) (unshaded) (unshaded) 2. Write each as a decimal: 6 a) 100 b) c) d) Write each as a decimal: a) fourteen and three hundredths b) fifty and sixty-two hundredths c) seventeen hundredths d) four hundredths e) ten hundredths f) one hundred hundredths 12 Marian Small, 2010 Representing and Comparing Decimals

13 Representing Decimal Hundredths 4. Write the words you say to read these. a) 3.01 b) 0.27 c) 2.18 d) To which whole number is each closest? a) 3.94 b) 5.17 c) is closer to 3.4 than to 3.5. What could the missing digit be? List at least three possibilities. 7. You can use the words two, fifty, four and hundredths to write a number that includes a decimal hundredths part. You may include other place value words or use a word more than once. a) List at least four numbers you could write. b) Tell how you would read each number hundreds > 3 tens. Explain why 0.03 < Marian Small, 2010 Representing and Comparing Decimals

14 Counting by Tenths or Hundredths Learning Goal reasoning about how to count by tenths or hundredths. Open Question We are labeling the points on a number line by skip counting. For example, we might say 0.2, 0.4, 0.6, 0.8,. or we might say 0.3, 0.6, 0.9,. 1. You skip count by a decimal amount and one of the numbers you say is 7.2. List the five numbers you might have said before 7.2 and the five numbers you would say after 7.2. Think of as many possibilities as you can. Tell what you are skip counting by You do the same thing but this time you say 0.72 instead of Marian Small, 2010 Representing and Comparing Decimals

15 Counting by Tenths or Hundredths Think Sheet When we count by 1 tenth, we say: 1 tenth, 2 tenths, 3 tenths,. and write 0.1, 0.2, 0.3,. When we get to 10 tenths, we write 1.0 and not That s because 1.0 (which is 1 and 0 tenths, or 1) is 10 tenths. When we count by 2 tenths, we say: 2 tenths, 4 tenths, 6 tenths, and would write 0.2, 0.4, 0.6, 0.8, 1.0, When we count by 3 hundredths, we say: 3 hundredths, 6 hundredths, 9 hundredths, and would write 0.03, 0.06, 0.09, 0.12, We use this counting strategy when we want to mark the numbers on a number line to be an equal distance apart. 1. Continue the count for 5 more numbers: a) 3.2, 3.4, 3.6,,,,,. b) 0.51, 0.54, 0.57,,,,,. c) 0.3, 0.5, 0.7,,,,,. d) 1.84, 1.87,,,,,. 2. a) How many numbers will you say to get to 3.2 if you count: 0.1, 0.2, 0.3,? b) How many numbers will you say to get to 3.20 if you count: 0.01, 0.02, 0.03,? 15 Marian Small, 2010 Representing and Comparing Decimals

16 Counting by Tenths or Hundredths 3. Is it possible to skip count by something other than 0.1 or 0.01 so that one of the numbers you say is the one listed? Explain. a) 0.44 b) , 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, Why is 0.10 and not the number that comes after 0.09? 5. Draw a number line that shows at least 5 properly spaced numbers including Tell how you know that 0.48 is in the proper place. 16 Marian Small, 2010 Representing and Comparing Decimals

17 Renaming Decimal Tenths Learning Goal using the patterns of the place value system to rename decimal tenths. Open Question A penny is 0.01 ( 1 a dollar. 100 ) of a dollar since it takes 100 pennies to make A dime is 0.1 ( 1 ) of a dollar since it takes 10 dimes to make a dollar. 10 A dime is also 10 pennies so 0.10 is the same as 0.1. = = List five decimals that could be described as either tenths or hundredths. Include one decimal that is greater than 1. For each one, tell both ways the decimal could be read. Tell what it is about the decimal that lets you read it more than one way. 17 Marian Small, 2010 Representing and Comparing Decimals

18 Renaming Decimal Tenths Think Sheet A penny is 0.01 ( 1 a dollar. 100 ) of a dollar since it takes 100 pennies to make A dime is 0.1 ( 1 ) of a dollar since it takes 10 dimes to make a dollar. 10 But a dime is also 10 pennies, so 0.10 is the same as The picture shows why 2 tenths, or 0.2, is the same as 20 hundredths or Decimal tenths can also be greater than For example, 1.7 is 1 and 7 tenths or 17 tenths. Ones Tenths Hundredths Ones Tenths Hundredths But 1.7 = 1.70, so it is also 170 hundredths. That is because 170 hundredths = 100 hundredths (a dollar) and 70 hundredths (70 pennies). It is also 100 hundredths + 7 tenths or 10 tenths + 7 tenths. 1. Complete using numbers or one of the words tenths or hundredths: a) 3 tenths = hundredths b) 7 tenths = hundredths c) 50 hundredths = tenths d) 80 hundredths = tenths e) 8 = 80 f) 40 = 4 18 Marian Small, 2010 Representing and Comparing Decimals

19 Renaming Decimal Tenths 2. Write each of these as hundredths: a) 1.0 b) 1.2 c) a) Draw a picture to show why 0.3 = Explain. b) Draw a picture to show why 0.03 is not equal to Explain. 4. a) Why can a decimal tenth always be written as a decimal hundredth? b) Why can a decimal hundredth not always be written as a whole number of decimal tenths? 19 Marian Small, 2010 Representing and Comparing Decimals

20 Renaming Decimal Tenths 5. Use the numbers to fill in the blanks is tenths or hundredths. That s because each hundredths is tenth. is hundredths. That s the same as tenths and hundredths. can be read three ways. It can be hundredths, tenths, or 3 ones. 20 Marian Small, 2010 Representing and Comparing Decimals

21 Comparing Decimal Tenths or Hundredths Learning Goal reasoning about how two decimal tenths or two decimal hundredth values can be compared. Open Question 1. Think of a sport where scores are given as decimal tenths between 0.0 and Make up the names for 5 students participating in the sport. Give each player a score, but make sure at least two of the scores are really close together. Explain why they are close together. List the scores in order from the least to the greatest. Tell how you know your order is correct. 21 Marian Small, 2010 Representing and Comparing Decimals

22 Comparing Decimal Tenths or Hundredths 2. Think of a sport where scores are given as decimal hundredths between 0.00 and Make up the names for 5 students participating in the sport. Give each player a score; make sure at least three of the scores are between 6.00 and List the scores in order from the least to the greatest. Tell how you know your order is correct. 22 Marian Small, 2010 Representing and Comparing Decimals

23 Comparing Decimal Tenths or Hundredths Think Sheet When we compare fractions, we know that if the denominator is the same, the fraction with the greater numerator is more. For example, 4 5 > 2 5. If we compare two decimal tenths or two decimal hundredths, we can use the same idea. 0.3 > 0.2 since 3 10 > > 0.05 since > Another way to show this is using grids or base ten blocks. Using grids: > 0.2 since more is shaded > 0.05 since more is shaded. 23 Marian Small, 2010 Representing and Comparing Decimals

24 Comparing Decimal Tenths or Hundredths Using base ten blocks: If the flat is worth 1, the rod is worth 0.1 since 10 rods make 1 and the small cube is worth 0.01 since 100 small cubes make > 0.2 since 3 rods are more than 2 rods > 0.05 since 17 small cubes are more than 5 small cubes Marian Small, 2010 Representing and Comparing Decimals

25 Comparing Decimal Tenths or Hundredths We might want to know to what whole number a decimal is closest to or maybe to what decimal tenth a decimal hundredth is closest. This is sometimes called rounding. For example, if someone jumps 3.47 m, that is closer to 3.5 m than to 3.4 m and it is closer to 3 m than to 4 m. The grid shows that 0.47 is almost 0.5, so 3.47 is almost Circle the greater amount: a) 3 hundredths 12 hundredths b) 93 hundredths 19 hundredths c) 7 tenths 6 tenths d) 12 tenths 7 tenths 2. Write the decimal shown by the shaded part of each grid. Circle the one which is greater. a) b) c) 25 Marian Small, 2010 Representing and Comparing Decimals

26 Comparing Decimal Tenths or Hundredths 3. Write the decimal each set of blocks shows. Tell which is greater a) b) 26 Marian Small, 2010 Representing and Comparing Decimals

27 Comparing Decimal Tenths or Hundredths c) d) 4. What is the nearest whole number and the nearest decimal tenth for each? Number a) 0.28 b) 0.91 c) 1.43 d) 1.78 Rounded to nearest whole number Rounded to nearest decimal tenth 5. How do you know that 3. > 2. no matter what values are missing? 27 Marian Small, 2010 Representing and Comparing Decimals

28 Comparing Decimal Tenths or Hundredths 6. Use all of the digits below to fill in the blanks to make this true in two different ways.. >. >. > >. >. > Marian Small, 2010 Representing and Comparing Decimals

29 Comparing Mixed Decimals Learning Goal reasoning about how decimal tenths can be compared to decimal hundredths. Open Question Some students measured how far they could jump in metres. 0 cm Some of them measured using decimal tenths.. Some of them measured using decimal hundredths.. List ten possible measurements they could have used. Make sure that: some are decimal tenths some are decimal hundredths at least two pairs of distances are really close together Tell which distances are close together and how you know. List the distances in order from the least to the greatest. Tell how you know your order is correct. 29 Marian Small, 2010 Representing and Comparing Decimals

30 Comparing Mixed Decimals Think Sheet Just like fractions, it is often easier to compare decimals when they are described in the same units than when they are in different units. For example, to compare 0.7 and 0.34, we might say 0.7 is also 0.70, 70 so 100 > 34 and 0.7 > This is true even though 7 < 34. That is because 0.7 is 70 hundredths, not 7 hundredths. Another reason why 0.7 > 0.34 is: 0.7 is 7 tenths, but 0.34 is not even 4 tenths; it is only 3 tenths and a little more. We can use grids or base ten blocks to help us compare decimals. Using grids: Since more is shaded, 0.7 > Using base ten blocks: 0.7 is more than Marian Small, 2010 Representing and Comparing Decimals

31 Comparing Mixed Decimals 1. Circle the greater amount: a) 3 tenths 12 hundredths b) 9 hundredths 2 tenths c) 7 tenths 85 hundredths d) 42 hundredths 3 tenths 2. Write the decimal each set of blocks shows. Tell which is greater. a) b) c) d) 31 Marian Small, 2010 Representing and Comparing Decimals

32 Comparing Mixed Decimals 3. Draw a picture to show why each is true. a) 0.5 > 0.12 b) 0.85 > 0.4 > List a decimal tenth just a little more than each one. a) 0.23 b) 0.94 c) 1.49 d) How do you know that 3. > 2. even though 2. has more digits in it? 6. 1 metre = 100 cm, so 1 cm = 0.01 m. a) Put these distances in order from shortest to longest: 0.5 m 0.23 m 0.89 m 1.4 m b) Prove that you would get the same order if you wrote the measurements in centimetres. 32 Marian Small, 2010 Representing and Comparing Decimals

33 Comparing Mixed Decimals 7. List five ways to make each statement true using the digits 0, 1, 2, 3, 4, and 5 in the blanks,. >.. >.. >.. >.. >. 33 Marian Small, 2010 Representing and Comparing Decimals

34 Fraction Circles and Ten Frames 34 Marian Small, 2010 Representing and Comparing Decimals

35 Place Value Chart (1) Tens Ones Tenths Hundredths Tens Ones Tenths Hundredths 35 Marian Small, 2010 Representing and Comparing Decimals

36 Place Value Chart (2) Tens Ones Tenths Tens Ones Tenths 36 Marian Small, 2010 Representing and Comparing Decimals

37 Place Value Chart (3) Ones Tenths Hundredths Ones Tenths Hundredths 37 Marian Small, 2010 Representing and Comparing Decimals

38 10 10 Grid (1) 38 Marian Small, 2010 Representing and Comparing Decimals

39 10 10 Grids (2) 39 Marian Small, 2010 Representing and Comparing Decimals

40 100 Grids 40 Marian Small, 2010 Representing and Comparing Decimals

41 Number Lines 41 Marian Small, 2010 Representing and Comparing Decimals

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