In a double lesson, Year 5 pairs build a rectangle explorer in the Desmos graphing calculator for Year 4, who are starting perimeter. The teacher's starter graph, opened from a link without signing in, holds one rectangle whose corners depend on two sliders, w and h. Each pair sets the sliders to whole numbers from 1 to 12, types a rule for the area, A = w × h, and one for the perimeter, and checks them against rectangles worked out in their books: 7 by 3 should show 21 and 20. A common first rule, P = w + h, shows 10, and pairs fix it. They add a fixed-fence version in which h is a rule, h = 12 − w, so the perimeter stays at 24, and type three challenges in a note, such as finding the fenced rectangle with the largest area. Year 4 visit with their teacher for twenty minutes and try the explorers while the authors watch without helping and note every wrong turn. Pairs then rebuild: a slider that reached 12 and flattened the fenced rectangle now stops at 11, and unclear challenges are reworded.
This page is one of a growing set of PICRAT examples by cell, subject and grade. Page maintained by Andy Perryer.