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# Week 7 - 9 Length and perimeter

National curriculum content

• Measure, compare, add and subtract lengths
• Measure the perimeter of simple 2-D shapes

Lesson objectives

1. Measure length
2. Measure length (m)
3. Equivalent lengths – m & cm
4. Equivalent lengths – mm & cm
5. Compare lengths
6. Compare lengths
8. Subtract lengths
9. Measure perimeter
10. Calculate perimeter

What we want children to know

• Use different measuring equipment including rulers, tape measures, metre sticks and trundle wheels
• Measure larger objects using metres
• Think about whether it is better to measure items in centimetres or metres
• Recognise that 10 mm is equivalent to 1 cm
• Compare lengths of objects using comparison language and symbols
• Use language such as longer than, shorter than, taller than, longest, shortest and tallest
• Convert measurements to the same unit of length to add
• Explore the most efficient way to calculate and develop their mental addition strategies
• Measure the perimeter of simple 2D shapes
• Explore different methods for calculating the perimeter of a shape

What skills we want children to develop

Use knowledge to solve reasoning and problem solving questions such as:

Position the symbol:

Place the correct symbol between the measurements > or <

e.g. 306cm __ half a metre

Testing conditions:

A square has sides of a whole number of centimetres. Which of the following measurements could represent its perimeter?

8cm                18cm              24cm              25cm

Top tips:

Ahmed’s ruler is broken. Explain how he can still use it to measure things in the classroom.

Mathematical talk

• What unit of measure would be best to measure ____?
• How many millimetres are in ½ cm?
• Which symbols can we use to compare lengths?
• Why does converting the measurements to the same unit of length make it easier to add them?
• What is the most efficient way to subtract mixed units?
• What is perimeter? How can we calculate the perimeter of each shape?
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