teaching resource

Estimating Sums and Differences Interactive Activity

Updated: 20 Oct 2023

Download our interactive activity designed to sharpen your students’ understanding of estimating sums and differences with rounding and compatible numbers.

Editable: PowerPoint, Google Slides
Pages: 1 Page
Years: 3 - 4

Curriculum

VC2M3N06

Estimate the quantity of objects in collections and make estimates when solving problems to determine the reasonableness of calculations <ul> <li>estimating how much space a grid paper representation of a large number such as 20 200 will take up on the wall and how much paper will be required</li> <li>estimating the number of people in a large gathering (for example, a school assembly) using known numbers (such as how many students per class)</li> <li>choosing which place value they would estimate to for different situations; for example, choosing to estimate to the nearest ten when estimating how many dots on a ladybird or choosing to estimate to the nearest thousand when estimating crowd sizes at a venue</li> <li>checking the reasonableness of an addition calculation by using two- and three-digit numbers to the nearest ten or hundred to estimate; for example, using 200 + 400 = 600 to estimate and check the solution to the calculation 219 + 385</li> </ul>
VC2M4N07

Choose and use estimation and rounding to check and explain the reasonableness of calculations, including the results of financial transactions <ul> <li>using proficiency with basic facts to estimate the result of a calculation and say what amounts the answer will be between; for example, 5 packets of biscuits at $2.60 each will cost between $10 and $15 as 5 × $2 = $10 and 5 × $3 = $15</li> <li>using rounded amounts to complete an estimated budget for a shopping trip or an excursion, explaining why overestimating the amounts is appropriate</li> <li>recognising the effect of rounding in addition and multiplication calculations; rounding both numbers up, both numbers down, and one number up and one number down, and explaining which is the best approximation and why</li> </ul>

teaching resource

Estimating Sums and Differences Interactive Activity

Updated: 20 Oct 2023

Download our interactive activity designed to sharpen your students’ understanding of estimating sums and differences with rounding and compatible numbers.

Editable: PowerPoint, Google Slides
Pages: 1 Page
Years: 3 - 4

Download our interactive activity designed to sharpen your students’ understanding of estimating sums and differences with rounding and compatible numbers.

What Are Compatible Numbers?

You may be teaching your year 3 and 4 students how to estimate sums and differences with whole numbers. One method is to teach them how to round to the nearest 10, 100 or 1000 to solve a problem. Another method is to use compatible numbers. If you are new to teaching this concept, or perhaps you’ve been away from this maths concept for a while, let’s take a quick look at what compatible numbers are and how they are used with estimation.

Compatible numbers are ‘friendly numbers’ that are easy to work with when performing mental calculations or estimating maths problems. They are typically numbers ending in 5 or 0 to make calculations easier.

As an example, if your students want to estimate the sum of 227 + 171 with compatible numbers, you can guide them to use multiples of 25 to help them create a friendly number 225 + 175 might be an easier problem for them to compute mentally.

Let’s Get Estimating! Addition and Subtraction Style

If your students are in need of some additional practise with rounding and compatible numbers, you have come to the right place! Teach Starter has created a set of interactive slides to help your students sharpen their estimation skills. This teacher-created resource includes 9 different activities for students to complete.

Round to estimate (tens place)
Round to estimate (hundreds place)
Round to estimate (thousands place)
Estimating sums and differences maze
Drag and drop with compatible numbers
Extend lines to find the correct answer to a rounded equation
Compatible numbers matching game
Writing word problems
Determining a possible equation for an estimated sum

Easily Prepare This Estimation Activity for Your Students

If you are ready to send this activity to your students to complete, head on over to the green download button to choose from the PowerPoint or Google Slides version of this resource. If you select the Google Slides option, you will be prompted to make a copy of the resource before accessing it.

To complete the activities, guide the students to keep the slides open in ‘Edit’ mode so they can drag and drop, type in answers and complete all of the activities.

This resource was created by Kaylyn Chupp, a Teach Starter Collaborator.

More Resources for Your Estimation Lesson Plans!

Don’t stop there! We’ve got more activities and resources that cut down on lesson planning time:

[resource:5001390] [resource:5002325]

Curriculum

VC2M3N06

Estimate the quantity of objects in collections and make estimates when solving problems to determine the reasonableness of calculations <ul> <li>estimating how much space a grid paper representation of a large number such as 20 200 will take up on the wall and how much paper will be required</li> <li>estimating the number of people in a large gathering (for example, a school assembly) using known numbers (such as how many students per class)</li> <li>choosing which place value they would estimate to for different situations; for example, choosing to estimate to the nearest ten when estimating how many dots on a ladybird or choosing to estimate to the nearest thousand when estimating crowd sizes at a venue</li> <li>checking the reasonableness of an addition calculation by using two- and three-digit numbers to the nearest ten or hundred to estimate; for example, using 200 + 400 = 600 to estimate and check the solution to the calculation 219 + 385</li> </ul>
VC2M4N07

Choose and use estimation and rounding to check and explain the reasonableness of calculations, including the results of financial transactions <ul> <li>using proficiency with basic facts to estimate the result of a calculation and say what amounts the answer will be between; for example, 5 packets of biscuits at $2.60 each will cost between $10 and $15 as 5 × $2 = $10 and 5 × $3 = $15</li> <li>using rounded amounts to complete an estimated budget for a shopping trip or an excursion, explaining why overestimating the amounts is appropriate</li> <li>recognising the effect of rounding in addition and multiplication calculations; rounding both numbers up, both numbers down, and one number up and one number down, and explaining which is the best approximation and why</li> </ul>

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