One frustration I encountered last year in my geometry classes involved the Distance and Midpoint formulas. Our text book and I made the assumption that since my students had worked with these formulas, they would remember them and could use them. We encountered problems throughout the book that required the use of both formulas and I had to stop at one point and reteach them. An insight occurred when a student mentioned that m (from slope) stood for midpoint, so I can see where confusion can occur.
The following Geogebra applets should help us explore and learn about midpoint and, hopefully, be able to find it throughout our course of study and in future math classes.