Recording Two Ways

The students make sets of pasta shapes and count some away, then record the subtraction in vertical and horizontal formats. They draw a set and cross out some shapes, then write in both formats the subtraction that the drawing represents.

How Many Left?

This lesson encourages the students to explore the familiar set model of subtraction. The students write story problems and find differences using sets, including subtracting all and subtracting zero. They record the differences in a chart.

Where Will I Land?

In this lesson, the students find differences using the number line, a continuous model for subtraction. [Number can be considered in two ways: discrete and continuous. The counting and set models use the discrete form of number.] Students are encouraged to predict differences and to compose puzzles involving subtraction.

What Balances?

This lesson encourages students to explore another meaning of subtraction, the balance. They use subtraction facts to generate related addition facts and explore at the concrete level the idea of subtraction as the inverse of addition.

Who's in the Fact Family?

In this lesson, the exploration of the relation of addition to subtraction is continued as the students use problem-solving skills to find fact families, including those in which one addend is zero or in which the addends are alike.

What's the Difference?

During this lesson, students use reasoning to find differences from numbers up to 10, using real and virtual calculators and an addition chart as tools. They also play a concentration game.

Baby Weight

In this lesson, students work with data to complete an organized chart by doubling or halving numbers. Then, they compare data using vertical and horizontal bar graphs.

What's the Beat?

In this activity, students use the average adult's number of heartbeats per minute to predict how many times the heart would beat during various lengths of time. The students also draw conclusions on the basis of information about the human heart rate and that of other animals.

Take Away

The following lesson introduces elementary students to subtraction. The objective is to create a link between students' experiences and mathematics. By the end of the lesson it is expected that students have a deep understanding of subtraction and how it relates to their world. This lesson was adapted from "Helping Students Understand Subtraction" by Anita Page, which appeared in the November 1994 Teaching Children Mathematics, Vol. 1, No. 3.