3.NBT.2. Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.

Addition - Crystal Crash
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 will work on any device in your browser.

Game availability:

Online in HTML5 format
Addition - Crystal Crash ?
Subtraction - Crystal Crash
The game was designed to cover all the mental subtraction objectives in the new maths curriculum. You can choose one objective, or choose all the objectives for a year group.

This game will work on any tablet or computer.

Game availability:

Online in HTML5 format
Subtraction - Crystal Crash ?
Addition - Digit Drag
Drag the digits to make a given sum. Lots of choice over level. A great starter activity for discussions on place value, mental methods of calculations and problem solving.

Game availability:

Online in HTML5 format
Addition - Digit Drag ?
Balancing Sums
An excellent tool for reinforcing an understanding of the role of the equals sign. Choose one objective, or many. You can choose all the objectives for a single year group (or multiple year groups). You can also choose to balance between different types of calculations (eg addition and multiplication).

For more addition and subtraction resources click here.

Game availability:

Online in HTML5 format
Balancing Sums ?
Balance scales - add, move or remove a weight
Balance the scales by adding, moving or removing a weight. A great mental starter to develop addition and subtraction skills.

For more addition and subtraction resources click here.

Game availability:

Online in HTML5 format
Balance scales - add, move or remove a weight ?
Difference using an unmarked number line
Find the difference between two numbers by counting on from the smaller number to the larger number. Children must add the fewest numbers possible, so are encouraged to develop more efficient mental methods. The addition is also shown as jumps on a number line.

Levels include counting up to 10, 20, 50 or 100, finding the difference between 2-digit numbers, 3-digit numbers and decimals.

For more addition and subtraction resources click here.

Game availability:

Online in HTML5 format
Difference using an unmarked number line ?
Difference using a marked number line
Count on from the smaller number to the larger. As numbers are added to the balance scale they are also shown on the number line. Children should be encouraged to use their knowledge of number bonds to develop efficient mental methods.

Levels include counting up to 10, 20, 50 or 100, finding the difference between 2-digit numbers and decimals.

For more addition and subtraction resources click here.

Game availability:

Online in HTML5 format
Difference using a marked number line ?
Balancing Scales g and kg
Add weights to either pan until they are balanced. Can be used to teach addition, subtraction, partitioning, and mass, as well as developing an understanding of the equals sign.

Choose from grams, whole kilograms or kilograms with either 1 or 2 decimal places.

For more addition and subtraction resources click here.

For more partitioning resources click here.

Game availability:

Online in HTML5 format
Balancing Scales g and kg ?
Number Bonds
Find pairs of numbers with a given total. Play against the clock.

For more addition and subtraction resources click here.

Game availability:

Online in HTML5 format
Number Bonds ?
Expanded Addition
Add the partitioned numbers beginning with the largest. Choice of 2-digit, 3-digit or 4-digit numbers. An important conceptual step before a more formal method of column addition.

For more addition and subtraction resources click here.

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 and the App Store.

Game availability:

Online in HTML5 format
Expanded Addition ?
Missing Symbols
Drag the symbols to the correct position to make the number sentence correct. Lots of levels to play. See if you can improve your score over time.

For more multiplication and division resources click here.

For more addition and subtraction resources click here.

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 and the App Store.

Game availability:

Online in HTML5 format
Missing Symbols ?
Expanded Addition using Place Value Counters
A step towards a more formal written method of columnar addition.

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 and the App Store.

Game availability:

Online in Flash format
Expanded Addition using Place Value Counters ?