Year 5 know that two rectangles can share an area and have different perimeters, and this lesson tests that idea on a real shape. On one laptop per pair, children open Google Earth in the browser, which the school's administrator has switched on for pupil devices beforehand, and find the boating lake in the town park. Using the measure tool, they click round the shore until the outline closes, and the tool reports its perimeter in metres and its area in square metres. Their first outline uses 6 clicks from high up, the second 15, and for the third they zoom in on each inlet and use about 40. One pair's table reads 380 m and 7,400 m², then 440 m and 8,100 m², then 520 m and 8,300 m². Pairs compare tables, and the teacher asks why the perimeter grew by 140 m while the area hardly moved after the second outline. Children then predict what will happen on the football pitch beside the lake, test it with 4 clicks and then 12, and write an explanation of why a wiggly edge adds perimeter without adding much area.
Tools: Google Earth Nine ideas for your own version in Generate
This page is one of a growing set of PICRAT examples by cell, subject and grade. Page maintained by Andy Perryer.