University of Saskatchewan: Techniques for Proofs

The University of Saskatchewan's Department of Mathematics and Statistics provides high school students with online tutorials and exercises on what they deem some of the most important techniques for mathematical proofs: truth tables, quantifiers, direct proofs, indirect proofs, and mathematical induction. In-depth lessons, along with accompanying examples are found by clicking on the different topic titles. Students can then test their skills on a series of increasingly more difficult exercises. These problem sets have accompanying hints and solutions.