Alfie is helping Uncle Paul work out how much paint to order for the living room by calculating the area of the rectangular walls. They then decide to order some rectangular tiles for the bathroom floor and need help working out which sizes to purchase.
More resources for Autumn Block 5 Step 3.
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Discussion points for teachers
1. Which formula should we use to calculate the area of the rectangular wall? What information do we need?
Discuss the method of measurement and formula used to calculate the area of a rectangle, including how to record answers.
The formula for calculating the area of a rectangle is length x width. Alfie and Uncle Paul need to know the length of the wall and the width (or height in this case).
2. Estimate the area of the wall.
Discuss how to round decimal numbers to the nearest whole number and then use the formula correctly. Discuss which decimal numbers round up or down, and how rounding incorrectly may affect the result.
3.8m and 2.5m round up to 4m and 3m respectively. The estimated area of the wall is 4m x 3m = 12m².
3. Help Uncle Paul and Alfie calculate the area of the window.
Discuss the conversion of centimetres to metres so that the formula can be used accurately.
200cm = 2m; 2m x 1m = 2m²
4. Using the estimated area of the wall and the area of the window, calculate the area to be painted.
Discuss which calculation should be used to find the answer. Note that this is still an estimated area due to working with the result from question 2.
12m² – 2m² = 10m².
5. How many tins of paint should Alfie and Uncle Paul buy?
Discuss the fact that paint will be sold as full tins, and how to ensure there will be enough paint for the whole area.
If one tin of paint covers 9m², they will need 2 tins of paint to cover 10m².
6. The length of the bathroom is 3m and the area is 6m². If Uncle Paul can combine two types of tile, what possible floor designs could he have?
Discuss how to manipulate the formula to calculate the width of the bathroom. Using these dimensions, children to explore the possible combinations of two tile types to cover the area of the floor. This question is open-ended for the children to explore.
Various answers, for example: The below design uses tile A and tile B and covers the correct area. The width of the room is calculated as: 6m² ÷ 3m = 2m.
National Curriculum Objectives
Mathematics Year 5: (5M7b) Calculate and compare the area of rectangles (including squares), and including using standard units, square centimetres (cm2) and square metres (m2) and estimate the area of irregular shapes
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