Purpose: To add two fractions having different denominators of 10, 100, or 1000

Materials: Decimal Squares, Blank Decimal Squares (attached)

Activity 1 Equivalent fractions with denominators of 10, 100, and 1000 Decimal Squares

1. Show students or have them find the tenths Decimal Square with 3 parts shaded. a. What is the fraction for the shaded amount of the square? (3/10) b. Find a green square for hundredths with the same amount of shading. What is the fraction for the shaded amount? (30/100)

c. Write an equation to show that these two squares have the same amount of shading. (3/10 = 30/100) 2. Show the students or have them find a green square with 25 parts shaded. a. What is the fraction for this square? (25/100) b. Find a yellow thousandths square with the same shaded amount. What is the fraction for this square? (250/1000) c. Write an equation to show that these two squares have the same shaded amount. (25/100 = 250/1000) 3. Repeat this activity by having students find squares for other pairs of fractions and completing the equations.

a. 710

= 100

b. 6501000

= 100

c. 410

= 1000

d. 5100

= 1000

Activity 2 Adding fractions with denominators that are powers of 10 Decimal Squares

1. Show students or have them find squares for 6/10 and 75/100. a. What is the total shaded amount of these squares? (1 whole square and 35 parts out of 100) b. Discuss their methods for determining the total shaded amount. (Some students may see that 6/10 = 60/100 and

ADDITION 4.NF.5 Adding Fractions with Denominators of 10, 100, and 1000

TEACHER MODELING/STUDENT COMMUNICATION

add 60 hundredths and 75 hundredths to get 1 whole square and 35 hundredths. Show students that this method can be recorded by the following equations.

610

+ 75100

= 60100

+ 75100

= 135100

= 1 35100

Some students might place the shaded amounts of the squares for 6/10 and 75/100 side by side to see that the total shaded amount is 1 whole bar and 35 hundredths. 2. Show students or have them find squares for 725/1000 and 55/100, and write an addition equation for the sum of these fractions. 725

1000 + 55

100 = 725

1000 + 550

1000 = 1275

1000 = 1 275

1000

3. Ask each student to select two Decimal Squares of different colors, write the fraction for each square, and write an addition equation for the sum of the two fractions. Discuss some of their examples.

Activity 3 Shading Blank Decimal Squares to compute fraction sums Blank Decimal Squares

1. Distribute a sheet of Blank Decimal Squares to each student and select from the following sums. Students can shade one or more squares to show the total shaded amount for two fractions and circle the square or squares involved. The fractions for the squares and their sum can be written next to the square(s).

a. 610

+ 15100

b. 35100

+ 810

c. 910

+ 3501000

d. 80100

+ 501000

Discuss student approaches. Some students may shade three squares writing + and = between them. Others may use two different colors or types of shading on one square to show the total shaded amount as in the example here for 37/100 + 46/100. This provides opportunities to use the add-up or count-on method, that is, shade a square for one fraction and then continue shading for the second fraction.

Worksheet 4.NF.5 #1

INDEPENDENT PRACTICE and ASSESSMENT

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