1 Doctoral Program in Mathematics Education, Khon Kaen University, Khon Kaen, Thailand. 2 Mathematics Education Program, Faculty of Education, Khon Kaen University, Khon Kaen, Thailand. The objective ...

SHANGHAI — Seated in pairs, 8- and 9-year-old students open envelopes filled with paper shapes — triangles, squares, pentagons, hexagons, and octagons — and start playing around with them. Some fit ...