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1. PAPER: A Sketchpad Investigation involving triangles & quadrilaterals 8 pp. @ USD 0.25. (A dynamic sketch on which the article is based is available at dynamic sketch )
2. Lulu BOOK: Some Adventures in Euclidean Geometry 219 pp. @ USD 4.00 to download - printed copy also available @ USD 26.99. (This book seeks to actively involve the reader in the heuristic processes of conjecturing, discovering, formulating, classifying, defining, refuting, proving, etc. within the context of Euclidean geometry. Extensive attention is also given to the classification of the quadrilaterals from the symmetry of a side-angle duality. Many examples lend themselves excellently for exploration on computer with dynamic geometry programs such as Sketchpad.)
3. Lulu BOOK: Boolean Algebra at School, Vol 1 147 pp. @ USD 3.00 to download - printed copy also available @ USD 15.00. (The main focus of this book is on actively engaging students in the mathematical processes of modeling and axiomatization. The book starts off with some challenging problems involving switching circuits. Students are then engaged in gradually developing a mathematical model in order to solve these problems. Eventually students are led through some proof activities to identify a suitable set of axioms.)
4. Lulu BOOK: Boolean Algebra at School, Vol 2 121 pp. @ USD 2.20 to download - printed copy also available @ USD 11.00. (The Teacher's Guide to Vol 1, provides a more detailed discussion and formal exposition of Boolean Algebra as well as a few more examples of Boolean Algebras, as well as a rationale for the approach used in Volume 1.)
5. CHAPTER: Inductive & Deductive Reasoning: Logic & Proof 15 pp. @ USD 0.90 to download. (This chapter is from a discontinued book on "Mathematics Education for Preservice & Inservice Teachers". It discusses and distinguishes between inductive and deductive reasoning, and illustrates with examples, as well as briefly analyzing the importance of both for mathematics education.)
SPECIAL LULU BOOKS DISCOUNT, June 2011: Enter coupon code TOP305 at checkout and receive 20% off your order. The maximum savings for this coupon is $250. Offer good towards print costs only - shipping and tax amounts are excluded. You can only use the code once per account, and you can't use this coupon in combination with other coupon codes. This great offer ends on June 13, 2011 at 11:59 PM so try not to procrastinate!