Don’t throw away old envelopes because you can make a very nice Tetrahedron with them. Fold a triangle in one corner of a used envelope. Mark a line and cut it to get a double layer square because the envelope will have two layers. This square will have an open mouth. The other end will be closed. Double the envelope and mark the mid-point of the open end with a pen. Draw lines from this point to the opposite corners. Both these blue lines will be the same size and this way you will make an isosceles triangle. Crease both the blue lines sharply. And now as you open the mouth of the square, its edges will join and make a Tetrahedron. Tape the open end to finish the model. “Tetra” means four and “hedrons” means triangles so Tetrahedron means made of 4 triangles.
Now instead of ONE make TWO Tetrahedrons from a similar envelope. Because these two tetrahedrons are joined they can flex about a common edge. This opens up many possibilities. You can become more adventurous and tape together SIX tetrahedrons in the shape of a flower. You will be surprised to be able to continuously rotate this paper flower. You can draw a food chain, a cycle, sequence or tell a story wonderfully through this rotating model. This work was supported by IUCAA and Tata Trust. This film was made by Ashok Rupner TATA Trust: Education is one of the key focus areas for Tata Trusts, aiming towards enabling access of quality education to the underprivileged population in India. To facilitate quality in teaching and learning of Science education through workshops, capacity building and resource creation, Tata Trusts have been supporting Muktangan Vigyan Shodhika (MVS), IUCAA’s Children’s Science Centre, since inception. To know more about other initiatives of Tata Trusts, please visit www.tatatrusts.org