# Maths KS2: Adding and subtracting using mental methods

In a mythical temple full of obstacles, Olivia and Hassan learn simple mental maths and apply it to work out the passcode to open the door.

Hypatia, our great mathemagician, sets a question which they must work out correctly to open the door: 15,712 + 2200.

With the help of mathematical companion Archimedes, the pupils learn simple mental maths and apply it to work out the answer.

Once they have left the temple, Hypatia and Archimedes leave pupils with a further mental subtraction question.

This short animated film is from the BBC Teach series, Hypatia's Mathematical Maze.

### Teacher Notes

Before watching the film

Prior to this lesson you may want to introduce students to other relevant topics, for example:

• Place value including naming columns and recognising the value of individual digits, up to the 100,000s
• Partitioning numbers using standard and non-standard partitioning
• Counting in steps of powers of 10 from any number

During watching the film

Depending on your lesson’s focus, you may want to pause the video at certain points to check for understanding, asking questions such as:

• Which digits change and which don't? Why?
• Which column are you tackling first? Why? Does it matter?
• How can we solve Hypatia's question at the end?

Following on from the film

• You could practise conceptual variation and represent problems using a variety of concrete materials, e.g. dienes blocks and place value counters.
• You could practise procedural variation and give a sequence of questions and ask the pupils when the method or thinking changes, e.g.

• 17,245 + 1500
• 17,245 + 1600
• 17,245 + 1700
• 17,245 + 1800
• 17,245 + 1900
When does the pattern change? Do we need a different method?
• You could present some problems with some 'good mistakes' made, and ask the pupils to spot and correct them, e.g. 43,372 + 2400 = 45,870

### Curriculum Notes

This short film is suitable for teaching maths at KS2 in England, Wales and Northern Ireland and 2nd Level in Scotland.