I had tessellations in my math book in 7th and 8th grades (in the 60's) but it was devoted to one page and emphasized that in a tesselation, the sum of the angles at a particular point is 360 degrees. Thus, certain shapes like squares and hexagons tesselate while octagons do not. Octagons and squares can be made to tessellate, however. This is probably the emphasis in Singapore's program,though I haven't seen it.
What others are talking about here are the tessellations that involve the nesting/interlocking of designs. Mathematics takes a back seat to the art aspect of the activity.
Katharine Beals, PhD, is the author of "Raising a Left-Brain Child in a Right-Brain World: Strategies for Helping Bright, Quirky, Socially Awkward Children to Thrive at Home and at School" (Shambhala/Trumpeter)
Katharine is an educator and the mother of three left-brain children. She has taught math, computer science, social studies, expository writing, linguistics, and English as a second language to students of all ages, both in the U.S. and overseas. She is also the architect of the GrammarTrainer, a linguistic software program for language impaired children.
She is currently a lecturer at the University of Pennsylvania Graduate School of Education and an adjunct professor at the Drexel University School of Education.
This site uses left-brain and right-brainnot as physiological terms for the actual left and right hemispheres of the brain, but as they are employed in the everyday vernacular. They appear here in the same spirit in which people use type A and type B (themselves the relics of a debunked theory about blood type and character type): an informal shorthand for certain bundles of personality traits.