Link-Cube Addition

Task

Materials

• Link-cubes or snap-cubes (2 colors for each student or pair of students)

• A die

• Paper and pencil

Actions

1. Roll the die.

2. Using a single color, snap together the same number of cubes as is shown on the die.

3. Roll the die again.

4. Using the other color, snap together the same number of cubes as is shown on the die.

5. Snap the two groups of cubes together.

6. Write an addition equation that uses the number of each color of cube and the total number of cubes.

7. Write as many addition and subtraction equations as possible using the same three numbers.

IM Commentary

The purpose of this task is for students to identify and represent related addition and subtraction equations with objects and equations. While there are eight possible equations for every pair of numbers rolled that are different, students do not need to write all eight equations every time. A task that explicitly asks students to write all eight equations is 1.OA Fact Families with Pictures. A good follow-up to this task is 1.OA Fact Families.

This task would work well as a station if there is an adult to help explain the steps that students should follow. Alternatively, the teacher can show students what to do and then have them work individually or in pairs. The teacher may want to use different colored dice to correspond to the different colored link- or snap-cubes.

The advantage of using link- or snap-cubes is that they can help students understand length; see cluster 1.MD.A.

Solution

Suppose the first number rolled is a 4 and the second number rolled is a 5. Then the cubes might look like this:

Then one equation could be 4+5=9. Flipping the linked cubes around so the red ones are on the left and the green ones are on the right makes it easy to see another equation:

5+4=9

The other equations are:

9=4+5

9=5+4

9-4=5

9-5=4

5=9-4

4=9-5