4.5(C): Use models to determine the formulas for the perimeter of a rectangle…
Use models to determine the formulas for the perimeter of a rectangle (l + w + l + w or 2l + 2w) and the area of a rectangle (l × w).
The Texas Essential Knowledge and Skills (TEKS) for Mathematics outcome 4.5(C) (Algebraic reasoning) for Grade 4 says: “Use models to determine the formulas for the perimeter of a rectangle (l + w + l + w or 2l + 2w) and the area of a rectangle (l × w).” This Fieldbook unit teaches it hands-on, with everyday materials and a printable teacher guide and student sheet for every lesson. Official wording: Texas Essential Knowledge and Skills (TEKS) for Mathematics.
Fence It, Fill It: Area and Perimeter Grades 3–4
Which mat is really the biggest? Does the same fence always hold the same garden? Can the same rug need more edging? Four lessons where students tile, stretch rope and chalk the schoolyard to find out that area and perimeter measure different things.
- Does the same fence always hold the same garden? 50–60 min
Teams stretch the same 12 m rope loop into different rectangles in the schoolyard and find that a fence of the same length can hold 5, 8 or 9 square metres. Students find perimeter by adding the sides, find area by multiplying, and recommend a shape for a school garden.
- Can the same rug need more edging? 45–60 min
Teams build every rectangle they can from the same 24 square tiles and find that the edging around them runs from 20 to 50 tile edges. Students explain that the same area can have different perimeters, and use length × width = area to find a missing side.
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