Build upon your class's growing confidence adding and subtracting mentally by sharing and developing helpful strategies for solving increasingly complex calculations with larger numbers.

Knowing Number Facts includes slides with every lesson which clearly show how to apply place value knowledge when mentally adding or subtracting tens or hundreds, how to visualise missing number problems to better understand them, and how calculations may be made easier to solve mentally by performing the additions and/or subtractions in a different order.

Each of the five 'Knowing Number Facts' Maths lessons for Year 3 includes plans, slides, a choice of activities and a range of printable resources.

Adding Tens

Kickstart the week's learning by recapping the place value of digits in two- and three-digit numbers, and how this can help mentally calculate addition of tens, e.g. 136 + 40. The included slides go on to show a variety of strategies to help mentally solve calculations like these, including those where exchanging is required. During either of the included activities, your class will have the opportunity to put what they've learned into practice as they solve calculations written using a variety of mathematical language.

Mental Missing Numbers

Take a look at a variety of increasingly challenging missing number problems where tens or hundreds have been added or subtracted. The included slides clearly explain mental strategies for solving these, and the choice of differentiated activities provide plenty of opportunities for children to put their learning into practice.

Compensation Methods

Start with a quick look at the fundamentals: the place value of digits in numbers, and how knowing addition and subtraction facts about one-digit numbers helps us work out additions and subtractions of ten or a hundred times those amounts. After that, the slides clearly and simply explain how a compensation method may be used to make solving subtraction calculations mentally, easier.

Subtracting Again and Again

This lesson builds upon your class's prior understanding of subtracting tens and hundreds, focussing on solving tricky, longer calculations such as 128 - 10 - 30 - 20. They'll learn how the subtractions may be solved in any order, and how they can be added first. Children will consider which methods they already use, as well as these, they prefer when calculating mentally. After that there's a choice of fun activities where children can practise the skills they've developed while playing games.

Four and Eight

Kick off the day's Maths learning with a quick activity where children will count in multiples of four and eight. After that, take a look at how compensation methods can help mentally solve calculations where 8, 9, 80 or 90 are subtracted. After that, it's up to you which of the two activities your class undertake: writing and solving their own subtraction calculations, or doing a simple subtraction investigation.