Purpose

In this activity we look at cubes which have been roughly sorted into arrays and decide **about** how many there are. We use our knowledge of multiplication facts to estimate the number of cubes.

Achievement Objectives

NA3-2: Know basic multiplication and division facts.

Specific Learning Outcomes

use arrays to solve estimation problems

Required Resource Materials

Multilink cubes

Overhead projector (if available)

Activity

- Tell the students that you are going to show them some cubes and that they have to figure out
**about**how many there are. Tell the students that you will be asking them more than or less than questions. - Put 16 cubes on the projector, arranged roughly in 4 rows of 4. Display for a couple of seconds.
*Did you see more than 20 cubes? Why do you think that?* - Repeat the activity with a slightly different number of cubes. Say 17 cubes in 4 rows of 4 and a row of 5. More than 5 cubes per row and more than 5 rows is hard to visualise quickly.
*Did you see more than 20 cubes? Why do you think that?*

- Continue with different numbers of cubes.