This applet contains a Triangle with a Midsegment. You can move the vertices of the triangle and see how it affects the Midsegment.

Point D is the Midpoint of AC, and Point E is the Midpoint of CB; therefore, DE a Midsegment.[br]Move the vertices of the triangle until you think you could propose the Triangle Midsegment Theorem. There are 2 attributes that relate the Midsegment: DE to the 3rd side: AB.