Having high school students prove geometrical propositions became the norm in the United States with the reforms of the 1890's - when geometry was designated as the place for students to learn the ...

I first started teaching Geometry last year and have taken over "Informal Geometry" this year. As the name of the second class implies, the idea of formal proof is strongly de-emphasized; this class ...

Journal for Research in Mathematics Education, Vol. 33, No. 3 (May, 2002), pp. 176-203 (28 pages) This article uses a classroom episode in which a teacher and her students undertake a task of proving ...