Everyday Mathematics
Why a triangle’s angles add to 180 degrees on a flat surface
Use a paper triangle to explore the 180-degree angle sum, then connect the observation to a parallel-line argument that explains why it works.
LEARN · QUESTION · DISCOVER
geometry
Learning Mathematics
A shape can have rotational symmetry without mirror symmetry
Use paper shapes to distinguish turning symmetry from mirror symmetry and explain why one test does not replace the other.
Learning Mathematics
A Square Is a Rectangle With an Extra Condition
Help children classify squares and rectangles by their properties, using paper shapes, right angles and a simple sorting activity.