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 20 October 2014

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# Mental maths - lesson plan

### Objectives

To use a number machine to practise mental methods of calculating addition, subtraction, division and multiplication.

### National Curriculum

Ma2, 1e, 1i, 3d, 3f, 3g, 3h.

### Resources

• Online activities:
• Bitesize mental maths section: play, quiz
• Other resources:
• Set of mental maths questions, including breaking down, rounding, doubling, using inverse and multiplying and dividing by 10 and 100
• Number die, marked 1 to 12
• Operation cards, marked + and -
• Counters
• Interactive whiteboard
• Operation die
• Whiteboards or jotters
• Stopwatch

### Teaching activities

#### Introduction

1. Call out a maths question to the class with a missing operation (eg 1 ? 2 = 3).
2. Ask the children to show the answer by using their bodies to represent the missing symbol.
3. Choose a child who got the answer correct and ask them to pick a pre-written mental maths question and give it to the class.
4. After a selection of questions, ask the children to discuss with their group any methods they use to calculate sums quickly in their head.
5. Repeat with subtraction, multiplication and division questions.
6. Encourage the children to listen and share ideas.

#### Activity

Lower ability - Ask the children to work in small groups and set each other mental maths questions by using a 1 to 12 die and operation cards (marked + and -). Roll the number die, pick an operation card and then roll the number die again. Jot the resulting mental maths question on a whiteboard or jotter. See how quickly pairs can calculate these sums in their heads. Repeat. If the question is answered correctly the player gets a counter, the player with the most counters at the end wins.

Middle ability - Introduce the online activity to the group on the whiteboard. Demonstrate the number machine carefully. Go through three or four different rules so that the group understands how to use the activity.

Higher ability - Ask the children to work in pairs and set each other mental maths questions by using a 1 to 12 die and an operation die (marked 'add', 'subtract', 'multiply' and 'divide'). Roll the number die, roll the operation die and then roll the number die again. Jot the resulting mental maths question on a whiteboard or jotter. Use a stopwatch to see how quickly the pairs can calculate these sums in their heads. Repeat. If the question is answered correctly the player gets a counter. The player with the most counters at the end wins.

#### Plenary

1. Work through a couple more numbers on the machine from the Bitesize mental maths activity with the whole class.
2. Ask the children to guess the machine's rule.
3. Discuss with the children the best number to start with to try and calculate the rule. Does this work every time?

#### Extension

Ask the children to work through the Bitesize mental maths quiz.

#### Homework

If the children have internet access at home, ask them to attempt the online activity again. If not, suggest they ask a parent, carer or friend to give them quick-fire mental maths questions to answer.