This activity includes three separate TI-Nspire documents:
Introduction. Students find the sum of the angles and are asked to find missing angles. They also identify equilateral and isosceles triangles.
Constructions. Investigate whether triangles can be constructed with sides of any length.
Test. 13 interactive problems to test students' understanding.
There are associated pdf files providing a 4-sheet homework handout and a page of comments from students who have used this activity,