7th Grade: Pythagorean Theorem and Egyptian Knotted Ropes

My 7th Graders worked with the idea of knotted rope to understand how to prove that certain triangles are Right Triangles.


In the process, they learned about Pythagorean Triplets.

It is known that the Egyptians used a knotted rope as an aid to constructing right angles in their buildings. The rope had 12 evenly spaced knots, which could be formed into a 3-4-5 right triangle, thus giving an angle of exactly 90 degrees. Can you make a rope like this? Now use your knotted rope to check some right angles in your room at school or at home.