I think that when we use technology in the classroom with our students, we should teach them to use technology as a tool. One of the best applications for using a spreadsheet in class is in the solution of triangles. After my students have mastered the laws of sines and cosines with handheld calculators, and are familiar with the ambiguous case, I have them redo the same problems using excel.
It is a very challenging activity for them.
NOTE: Your students will need to have access to a comp