Grades 3-5 Math Problem Solving in Action_ Getting Students to Love Word Problems

Reasoning About Problems ◆ 105

Decimal bars are just as helpful as fraction bars. Here is an example
(see Figure 6.26).

Ken said that 7 hundredths is more than 2 tenths because 7 is greater

than 10. Michelle disagreed. She said that 2 tenths is bigger because

tenths are bigger than hundredths. Who is correct? Use a model to

justify your thinking.

Figure 6.26 Decimal Bars

1

0.50 0.50

0.33 0.33 0.33

0.25 0.25 0.25 0.25

0.20 0.20 0.20 0.20 0.20

0.166 0.166 0.166 0.166 0.166 .166

0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125

0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10

.083 .083 .083 .083 .083 .083 .083 .083 .083 .083 .083 .083

Using templates for two argument problems is also a way to scaffold
thinking.

Figure 6.27 Use Manipulatives, Sketches or Diagrams

Problem: Todd said that he ate ¼ of his candy bar. Mary said she ate ½ of

hers. Mary said she ate more than Todd because ½ is always bigger than ¼.

Todd disagreed.

Think about the arguments.

Who do think is correct?

Decide and defend your thinking.

Why did you think this?

Prove your thinking with a model. Prove your thinking with numbers.