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# Week 4- 6 Length and perimeter

National curriculum content

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

Lesson objectives

1. Measure in metres and centimetres
2. Measure in millimetres
3. Measure in centimetres and millimetres
4. Metres, centimetres and millimetres
5. Equivalent lengths (metres and centimetres)
6. Equivalent lengths (centimetres and millimetres)
7. Compare lengths
9. Subtract lengths
10. What is perimeter?
11. Measure perimeter
12. 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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