Combining and Comparing

We have been working on an addition and subtraction unit called Combining and Comparing. We've been focusing on interesting and real problems that involve combining and comparing two or more amounts.

Students will be learning about many different ways to solve addition and subtraction problems. Students will be encouraged to develop more than one way to solve a problem and to use methods that are based on understanding numbers and their relationships. Some of these methods you use in your daily life. We encourage students to develop strategies that make sense to them, that they can use easily and flexibly. For example, on of the first things we did is to compare the age of your family's oldest relative with the age of the oldest person on record (120 years old). Suppose your oldest relative is 83 years old. Your child might find the answer by seeing how many years you must add on to get from 83 to 120. Add 7 to 83 to get to 90, 10 more to get to 100, 20 more to get to 20. Another approach could be to subtract 80 from 120 to get 40, then subtract 3 more to get 37.

The point is for children to find useful and meaningful ways of putting together and taking apart numbers. While our class is working on this unit, you can help in several ways:

*When your child has an assignment to do at home--such as collecting data about the ages of pets and oldest relatives -- offer your help, and ask your child about what he or she is doing in class.

*Ask your child to describe any of the homework problems and tell you about the strategy used to solve it. Communication is an important part of mathematics, and students need to describe their strategies through talking, writing, drawing, or using concrete objects. You can be an important audience.

*You can also share your own ideas. At one point, we will work on the mathematics of "party planning". You might explain how you would figure out how to fit a number of different activities into a two-hour block of time.

An important emphasis in this unit is for students to recognize when and how to apply addition and subtraction and to develop procedures for adding and subtracting that they understand thoroughly and can use confidently. One of the most important things you can do is to show genuine interest in the ways your child solves problems, even if they are different from your own.

Thanks for your help and your interest in your child's mathematics.