Activities to Teach Students to Estimate Differences Using Compatible Numbers

Estimating differences using compatible numbers is an important skill for students to learn. Compatible numbers are numbers that are close in value to the actual numbers and are easy to work with when performing mental calculations. By using compatible numbers, students can make quick and accurate estimates of differences without having to use a calculator or pen and paper.

Here are some activities to help teach students how to estimate differences using compatible numbers.

1. Real-World Examples

One way to introduce students to the concept of estimating differences using compatible numbers is to provide real-world examples. For instance, students can estimate the difference in price between two items in a store. They could also estimate the difference in weight between two objects or estimate the difference in time between two events.

2. Number Line Activity

Create a number line on the board or on a worksheet with several points marked on it. Ask students to estimate the difference between two of the points using compatible numbers. For instance, if the number line has the points -20, -15, -10, -5, 0, 5, 10, 15, and 20, students could estimate the difference between -10 and 15 using compatible numbers such as 10 and 15.

3. Partner Game

Pair students together and give each pair a set of index cards with numbers between 1-50. Students take turns selecting two cards and estimating the difference between the two numbers using compatible numbers. The partner then checks the estimate using a calculator and gives feedback.

4. Estimation Jar

Fill a jar with objects such as marbles, buttons, or beads. Ask students to estimate the difference in the number of objects in the jar when some are removed or add, using compatible numbers. Challenge students to take turns modifying the jar’s contents and estimate the difference between the two collections.

5. Estimating Sports Scores

Ask students to make use of compatible numbers to estimate the difference in scores between two sports teams. This activity helps reinforce the concept of compatible numbers. Kids pick two popular teams and then, using the current score related to past games, estimate the difference scores.


Estimating differences using compatible numbers can be challenging for students to grasp at first. However, implementing these hands-on activities and real-world examples can help them understand the concept better. By providing students with plenty of opportunities to practice estimating differences using compatible numbers, they can become more efficient in mental calculations, leading to greater success in math.


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