Lesson Plan
Texas Instruments

Texas Instruments: Investigate Triangles and Congruence

For Teachers 9th - 10th Standards
Students can use the TI-84 Plus family with Cabri Jr. to prove triangle congruence with SSA.
Unit Plan
Texas Education Agency

Texas Gateway: Using Logical Reasoning to Prove Conjectures About Circles

For Students 9th - 10th Standards
Given conjectures about circles, the student will use deductive reasoning and counterexamples to prove or disprove the conjectures.
Website
National Council of Teachers of Mathematics

The Math Forum: Ask Dr. Math: Congruence and Triangles

For Students 9th - 10th Standards
This site gives a very thorough explanation of how to tell if two triangles are congruent. Dr. Math explains why SSS, SAS, ASA determine that two triangles are congruent. The Dr. gives a few exercises for the reader to try then gives the...
Unit Plan
Wolfram Research

Wolfram Math World: Rectangle

For Students 9th - 10th
MathWorld provides the definition of a rectangle and the area formula of a rectangle.