Monday, February 16, 2009

Modeling a Problem

We encourage students to visualize problems or create models for them if they do not understand what a problem is asking. Models are simply tools for thinking. We have problem solving strategy posters hanging in each second grade classroom to remind students of ways they can go about solving a problem if they do not understand it. Some of the posters include: make a chart or table, draw a diagram, guess and check, find a pattern, use logic, make it simpler, use real objects, or make a list. Let's take a look at how we can use some of these ideas to solve the problem below.

Miss Russell is getting ready for the Relay for Life. She needs 36 inches of tape to hang a sign over the Chets Creek booth. She heads to the store to buy the tape and realizes that they sell tape in feet, not inches. How many feet of tape will she need to buy to have the exact amount she needs to hang her sign? (She knows that 1 foot is equal to 12 inches.)

Your child may see problems similar to this one in Calendar Math. Students are discovering the relationship between units of measurement. (We have previously discussed the relationship in centimeters, decimeters, and meters.) As concepts are learned, we try to present them in a real-life context for students.

One thing that would help getting started with this problem would be to make it simpler. Find out what the problem is really asking. 12 inches = 1 foot so 36 inches = ? feet

Once students determine what the problem is asking, they can then use a strategy to help them. For this type of problem, students may want to make a t-chart or table to help show their thinking. Below are three student samples:

This student used three different strategies to model the problem. In strategy A, the student used a ratio table to show the relationship between inches and feet. In strategy B, the student used a t-chart to show the relationship between inches and feet. In strategy C, the student used a number line to hop by feet and write the inches beneath. All three are perfectly acceptable models to use to make sense of the problem.

1 comment:

Ashley Russell said...

Great Post! I love strategy A. The ratio table is a very mature and wonderful strategy. It is very easy to see the relationship between two numbers. This is a strategy that is used in many of the upper grades. Thanks for sharing! :)
-Miss Russell :)