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Net Lab

Surface area stops being a formula when the pieces are lying on the table in front of you.

✓ Free for everyone · works on a projector

1515151536

base + faces = 36 + 60 = 96

Volume 48

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Solid

Fold

Folded, you are looking straight down on the pyramid — that is why the faces meet in the middle.

Measurements

Apothem 3.00 · slant height l = 5.00 · sloping edge = 5.83. The slant height is the one in πrl's cousin — it runs up the middle of a face, not up a corner.

✓ This net can be cut from one sheet — no piece sits on another.

Four ways to use it in class

  1. Start folded and ask what the picture is. It is the view from directly above — and the faces meeting in the middle is the apex, seen end-on.
  2. Open it slowly. The pyramid's faces shrink to nothing on the way, because halfway through they are standing upright and you are looking at their edges.
  3. With it flat, add the numbers on the pieces out loud. That total is the surface area — no formula was needed to get it.
  4. Switch to the prism and ask why its net is a strip rather than a flower. Open a pyramid's and a prism's side by side: the triangles narrow to a point and fit, the rectangles do not.