Subtraction Games and Story Problems

The Investigations math curriculum is designed to engage students in making sense of mathematical ideas. The curriculum is designed to:

• Support students in learning that they can be mathematical thinkers
• Focus on computational fluency with whole numbers
• Provide substantive work in important areas of mathematics—geometry, measurement, data, and early algebra—and connections among them

In our math sessions, students engage in math problems and activities and discuss the underlying concepts.  They are asked to share their reasoning and solutions.  It is important that students solve problems accurately in ways that make sense to them. At home, please encourage your student to explain his or her mathematical thinking to you!

We start the year with a mathematics unit called Building Numbers and Solving Story Problems (Unit 1) from the Investigations in Number, Data, and Space Curriculum.  This unit is an introduction to mathematical ideas such as counting and comparing quantities, connecting counting to the operations of addition and subtraction and developing strategies for solving addition and subtraction problems through story problems and games.  

This week, students are focusing on using strategies to solve ever-more-complicated subtraction problems.

Today, they generated these strategies:

• use a number line to count and hop backwards
• draw the objects and cross off the amount to subtract.
• put the beginning number in your head and count backwards on your fingers
• use a fact you already know to help you (for example, if you know 5+5=10 then you can know 10-5=5–or if you know 15-5=10, then 15-6=9!)

One math game the students play, called Roll and Record Subtraction, helps them develop fluency with subtraction facts. They use number lines and previously known facts to solve subtraction problems. This game also gives a glimpse into probability and statistics: Which numbers are most likely to be the “winners” in this game?

In their math workbook, the students solve story problems in which they must identify whether the problem is addition or subtraction, write an equation, and show their work to prove their answer is correct.