Warm Up

• Write another subtraction problem that has a decimal difference that is less than the given difference and one with a decimal difference that is greater than the problem below.

6.2 – 3.37 = 2.83

Find Day 32 “Subtracting Decimals Using Models 1”

Subtracting Decimals Using Models Scenario 1

• Colin bought a package that has 4.5 feet of border for his science project display. He needs 3.8 feet of border. How many feet of border will Colin need to cut from the original package of border?

• Use what you know about decimals to estimate how many feet of border Colin will need to cut.

» 5 + 4= 9 miles

Subtracting Decimals Using Models Scenario 1

• Colin bought a package that has 4.5 feet of border for his science project display. He needs 3.8 feet of border. How many feet of border will Colin need to cut from the original package of border?•What subtraction sentence is

represented by the problem?

»4.5 - 3.8 = ?

4.5 - 3.8 = ?

• Let’s use Base Ten Pieces to model this addition sentence.– How would we represent 4.5 using Base Ten Pieces?

– 4 flats, 5 rods

– Take away 3.8• First take away 3 wholes.• Next we need to take away 8 rods• We only have 5 rods, where will we get the extra rods? • “Ungroup” a flat to make 10 rods, now take away the 8 rods.

– 4.5 - 3.8 = 0.7

Subtracting Decimals Using Models 1 Scenario 2

• Jasmine and Eunice built model cars to study force and motion. Jasmine’s car traveled 2.3 meters. Eunice’s car traveled 1.95 meters. How much farther did Jasmine’s car travel?

• Use what you know about decimals to estimate how much farther Jasmine’s car traveled.

» 2 – 2 = 0

Subtracting Decimals Using Models 1 Scenario 2

• Jasmine and Eunice built model cars to study force and motion. Jasmine’s car traveled 2.3 meters. Eunice’s car traveled 1.95 meters. How much farther did Jasmine’s car travel?•What subtraction sentence is

represented by the problem?

»2.3 – 1.95= ?• Use base ten pieces to solve this

problem.

2.3 – 1.95= ?

– Begin with 2 flats and 3 rods to represent 2.3– Take away 1 flat– “Ungroup” the other flat to make 10 rods– Take away 9 rods– “Ungroup” 1 rod to make 10 units– Take away 5 unit– 2.3 - 1.95 = 0.35

More practice see Day 32 “Subtracting Decimals Using

Models 2”

Using Base Ten Grids to Subtract

• Find Day 32 “Subtracting Decimals Using Models 3”• Elizabeth is 1.3 meters tall. Her little brother, David is

0.78 meters tall. How much taller is Elizabeth than David?– First, shade one whole (whole grid) and 3 tenths (3

columns of the second grid). – Then cross out 7 tenths by drawing a line through 7 of the

shaded columns.– Cross out 8 hundredths by drawing an “x” on 8 small boxes

in the next column.– 1.3 – 0.78 = 0.52

Remaining Time/Homework

• Day 32, “Subtracting Decimals with Base Ten Grids”

• Journal Prompt