The rekenrek

The rekenrek (Dutch for “counting rack”) was designed by Adri Treffers at the Freudenthal Institute in the Netherlands, around 1990, for teaching young children to count and add.

One thing to hold: Two rows of ten beads, five red then five white, so you can see five and ten at a glance.

Why it matters: Children learn to see 7 as “five and two more” instead of counting every bead one by one.

Sources: Adri Treffers, “Didactical background of a mathematics program for primary education”, in L. Streefland (ed.), Realistic Mathematics Education in Primary School (1991)