L.O. To find the perimeter of rectangles and composite shapes.
Re-cap how we find the perimeter of a shape. The perimeter is the outside of a shape. Do we need to measure all four sides of a rectangle to find the perimeter? The answer is no, because we know that the opposite side of a rectangle will be the same length.
Watch the video attached, which will demonstrate how to work out the perimeter of composite shapes.
Challenge 1
Make a set of flash cards between 1 and 9. Mix them, turn them face down and select two at a time. Use these numbers to make a rectangle e.g. 4 and 6 would be a 4cm by 6cm rectangle. Sketch it and find the perimeter. How many can you find in 2 minutes? Draw two of the rectangles on cm2 paper if possible, cut them out then put them together to form a new shape and find its perimeter. Sketch the shape, labelling each side. Then, compare the perimeter of the new shape with the total of the perimeters of the two rectangles. Repeat with other pairs of rectangles. Can you predict the perimeter of the new shape?
Challenge 2 Draw composite shapes on plain paper instead of squared paper.