If you'd like, could you say a little more about why this is the case? You ask a very pertinent question, to which other HN users have already replied. I'll li

If you'd like, could you say a little more about why this is the case? You ask a very pertinent question, to which other HN users have already replied. I'll link here to some articles by mathematicians who have considered how to do mathematics education well. When I just did a Google search on "fractions pizza slices" I had a HUGE number of hits, most to abominably bad materials for elementary teachers. Restricting the search in various ways found the links I share here, some of which I've read before and some of which are new to me too. ftp://math.stanford.edu/pub/papers/milgram/oregon-outline.pdf ftp://math.stanford.edu/pub/papers/milgram/oregon-presentation-2.pdf (Hacker News will not style these two as links, I think, but the URLs are valid.) http://math.berkeley.edu/~wu/Lisbon2010_2.pdf http://math.berkeley.edu/~wu/Lisbon2010_2.pdf (general audience version) http://math.berkeley.edu/~wu/Schoolmathematics1.pdf http://math.berkeley.edu/~wu/Schoolmathematics1.pdf (teacher version) http://steinhardt.nyu.edu/steinhardt/gateway/pdfs/Greenleaf_Fractions.pdf http://steinhardt.nyu.edu/steinhardt/gateway/pdfs/Greenleaf_... (a source new to me today) http://www.waset.org/journals/waset/v53/v53-66.pdf http://www.waset.org/journals/waset/v53/v53-66.pdf (another source new to me today) I hope this helps. The book I mentioned in my first comment in this thread is very good and well worth reading for any mathematics teacher.