Monthly Archives: December 2009
How to convert a “backwards” proof into a “forwards” proof
Dave Richeson at Division By Zero wrote recently about a “proof technique” for proving equalities or inequalities that is far too common: Starting with the equality to be proven and working backwards to end at a true statement. This is … Continue reading
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Filed under Abstract algebra, Geometry, Math, Problem Solving
Resisting the urge to verify
When I am having students work on something, whether it’s homework or something done in class, I’ll get a stream of questions that are variations on: Is this right? Am I on the right track? Can you tell me if … Continue reading
Filed under Critical thinking, Education, Math, Problem Solving, Teaching, Uncategorized
Some updates
Greetings, everybody. Is anybody still out there? It’s been a while. What started as a simple drop-off in the number of posts I was making here at Casting Out Nines turned into a five-month sabbatical from blogging at all. The … Continue reading
Filed under Blog announcements, Casting Out Nines
