Recognise and use the inverse relationship between addition and subtraction and use this to check calculations and missing number problems
Inverse Operations - Addition and Subtraction
I designed this resource to help children to visualise the relationship between addition and subtraction. They can then use this relationship to solve missing number problems. There are a wide range of levels, from adding within 20 to using a calculator to add and subtract 5 digit numbers and decimals.
I designed this activity to help children to visualise small differences between 2-digit numbers by bridging through multiples of 10. It can also be used to explore links between addition and subtraction and to begin to find differences using a number line.
This game is now part of the 'Calculations' collection, which includes the following 17 games and resources: Column Addition, Expanded Addition, Expanded Addition - Place Value Counters, Number Bonds(2), Addition - Digit Drag, Missing Symbols, Column Subtraction, Column Subtraction using Place Value Counters, Counting on to find difference on a beadstring, Multiplication Grid Method, Multiplication Written Method, Ratio and Scaling Numbers, Representing Multiplication, Division by Chunking Up, Division by Chunking Down, Formal Written Division - Round Up or Down?, Short Division Writen Formal Method.
The Calculations app is available on Google Play (£1.25) and will be available in the App Store in July.
A fun game to practise mental addition skills. The game was designed to cover all the mental addition objectives in the new math curriculum. You can choose one objective, or choose all the objectives for a year group.
This game, together with all the other crystal crash games, is available as a single iPad or Android app.
View full screen in your browser. This ITP displays up to 20 coloured counters and the corresponding addition sentence. The number of counters you select, appear on the screen in purple. Click on any counter to change its colour, the number sentence also changes. To hide and reveal the number sentence, click on the box with the question marks. You can replace a number in the number sentence with a question mark by clicking on the number, and drag counters around the screen to form groups. Addition can be changed to subtraction by clicking on the addition sign in the box. Counters can be dragged into the displayed box, which you can make opaque to hide the counters. The ITP can be used to model addition by combining and counting, and subtraction by partitioning and taking away. The hide and reveal options allow you to pose questions with unknown numbers in different positions in the number sentence. Partitioning counters in different ways helps children to identify all sums and differences of numbers to 20.