SE 3.10Constructive Triangles: Blue Rectangular Box (Box 2)

1. 1

   Take out the triangles and sort them by shape and size on the table.

2. 2

   Point out that these triangles have no black lines.

3. 3

   Pick up two triangles of the same shape and hold edges together to find two that are the same length.

4. 4

   Slide the triangles together along those edges and look at the figure; name it if the child knows it.

5. 5

   Turn one triangle, join a different pair of edges, and show the new figure made from the same two pieces.

6. 6

   Continue with the other pairs.

7. 7

   Place one figure on top of another to compare their sizes.

8. 8

   Return the triangles to the box.

What catches the child’s eye

• The same two triangles making a rectangle, then a parallelogram, with one turn
• Edges that line up with no gap once the right pair is found

Extensions, easiest to hardest

1. Build as many different figures as possible from one pair of triangles.
2. Lay two finished figures side by side and say how they are alike and different.
3. Draw each figure and color its two triangles.