What types of physical tools do you expect students and educators to use in the learning and teaching of geometric constructions? Although Euclid’s Elements remains silent on prescribing particular tools, do you expect learners and teachers to keep to the so-called Platonic restrictions? That is, are they limited to exploring geometric constructions with an unmarked […]

At the February GeT Seminar, Justin Dimmel made a compelling case for the use of light from the sun and stars as a naturally occurring context to study the geometry of parallel lines. One outcome of his work has been the ongoing development of a mathematical tool called the SunRule. By combining the geometry of […]

Sunlight provides an abundant, renewable, accessible source of naturally occurring rays that, for all intents and purposes, are parallel. It is the rare example of a real-world context with which nearly all children are familiar. Despite its familiarity and near universality, sunlight plays almost no part in K-12 mathematics classrooms. This is a missed opportunity […]

The mathematics education literature on student errors has documented how sometimes what students learn can be overgeneralized as they solve other problems and can even occasion errors. I was reminded of this as I puzzled over something I observed some Geometry for Teachers’ students doing as they worked on the problem of constructing a triangle […]