SamizdatMath

This is an activity that teaches students to classify acute, obtuse, straight and right angles using semaphore flag signals. Why semaphore flag signals? Because they're fun, interesting and "real." And also, they're a good example of how to teach a concept beyond the "prototypes." What do I mean by this? Well, do an image search on "right angle" and you'll see that the examples that show up are "textbook prototypes." That is, they all have a side resting on the horizontal, the other on the verti

"One, Some or None? Geometry" has a simple premise: if I gave you three clues about a geometric shape, would you be able to draw one, some or no kinds of shapes? This activity raises the bar on critical thinking and combines multi-model types of problem solving, as students draw examples (or non-examples) to support their ideas. This 40 page packet comes with clues for triangles ("has 2 equal sides," "has a right angle," etc.) and quadrilaterals ("has 1 set of parallel sides," "has 3 right ang

This 60 page booklet incorporates the theories of Pierre van Hiele and Dina van HIele-Geldorf, better known as the van Hiele Theory, to teach developmental geometry in elementary and middle school. The van Hiele's were pioneers in the understanding that children go through different levels of cognitive development in their understanding of geometric concepts, and that these levels changed with the age and education of the child. Through their work, we've come to understand what kinds of thinking