Estimating and checking answers – Year 3 maths lesson

Lesson 10 of 24 in the Year 3 maths course

UK version. UK school years, UK spelling and pounds (£). · US Math Department

A complete 45-minute lesson for Year 3 (ages 7–8) that runs on this page – at school or at home. Every answer is marked straight away, with a worked explanation.

Time: 45 minutes + 15 min homework
Year: Year 3 (ages 7–8)
You need: Paper, a pencil and this page
Marked: Instantly, with explanations

For parents: how to use this lesson

You don't need to know this topic yourself. The lesson explains each step on screen, one tidy step at a time. Every answer is marked straight away with a worked explanation, so you never have to mark anything.

Read what your child will learn and the big ideas together.
Press Start the lesson below and sit with your child for the teaching and the worked examples (about 19 minutes).
Let them do the practice on their own. They choose Getting started, On track or Challenge – start on On track and move up after a few right in a row.
Finish with the exit ticket and the talk question: “When is an estimate good enough, and when do you need the exact answer?”
Later that day or the next day: the homework (15 minutes), then a practice test.

Watch out for

Rounding and then giving the estimate as the exact answer. Use the estimate only to check the real calculation.
Rounding every number to 10 when they are in the thousands. Round to the leading digit for a quick estimate.

Tip for home: Estimate how long a journey or how much a shop will be, then check.

What your child will learn

We are learning to estimate answers by rounding, and use estimates to check calculations.

Success looks like

I can round numbers to estimate.
I can say if an answer is sensible.
I can choose how accurate an estimate needs to be.

Key words

estimate: a sensible, close answer worked out quickly
round: change to a nearby friendly number
accurate: close to the exact answer
check: make sure an answer is right

What to have ready

Paper and a pencil
This page on a computer, tablet or phone
For the hands-on part: Estimate the total of a few shopping items, then add them exactly and compare.

The big ideas (for the adult)

An estimate is a quick, sensible answer. Round each number to a friendly number first, then calculate.

If your exact answer is far from your estimate, check your working.

Choose how much to round: rounding less gives a closer estimate, rounding more makes it quicker.

The lesson, step by step

45 minutes in 5 parts
Part	Time	How it is checked
Starter: quick recall	5 min	Marked by Classfern
Teaching input	10 min	Not assessed, self-checked
Worked examples and guided practice	9 min	Not assessed, marked by Classfern
Independent practice	15 min	Marked by Classfern
Plenary and exit ticket	6 min	Marked by Classfern, self-checked

Starter, "your turn", practice and exit ticket are marked by Classfern. Worked examples and teaching are not assessed. The hands-on task and the reflection are self-assessed. Explanations in talk are judged by the parent and not recorded.

The lesson

It runs here on the page. No sign-up and no names – progress is kept only in this browser.

Homework and practice at home

15 minutes: 8 practice questions, 3 multiple-choice questions and 2 to remember from earlier work, then a short reflection. New questions every time, all marked instantly.

More practice

Year 3 addition and subtraction testMarked instantly

All Year 3 maths lessons and tests · Maths Department

Curriculum

National Curriculum for England, Year 3: “estimate the answer to a calculation and use inverse operations to check answers”

Contains public sector information licensed under the Open Government Licence v3.0.

Our lessons and questions are our own. They are not written or endorsed by any government department, testing agency or exam board.