Tricky triangles - Maths meets Science

We used force to make triangles of every possible shape. First we marked an elastic band into thirds with a marker pen, and then cut a length of string into thirds, tying one end to each mark on the elastic band.   Remembering force is a push or a pull, we worked in groups of three to pull one end of string to make different shaped triangles.  We knew the elastic shapes were triangles because they all had three sides and three angles.