Origami (折り紙)

			Analyzing folding on a square paper

A fold on a square paper

A fold on a rectangular paper

A fold on an A4 paper

Folding two opposite vertices of a square paper

Make a special triangle with a square paper

Fold to make a bisector of a triangle

Distinguishing bisectors of a triangle

			Mon-kiri (紋切り)

Making shapes with reflectional symmetry

060415i_worksheet.ggb

Make a fold on half of a square paper, the first step for folding a regular hexagon or regular pentagon. The methods are based on folding a 60 deg angle at center (for hexagon) and an approximate of 36 or 72 deg angle (for pentagon).

			These methods are explained in: 1. Unfolding Mathematics with Unit Origami by Betsy Franco, Activity 6 & 8. 2. Amazing Origami by Kunihiko Kasahara, pp.18 & 28-29 3. The Regular Pentagon by Jim Loy (http://www.jimloy.com/geometry/pentagon.htm) , addendum #2

			Here are photos of some examples of mon-kiri.

Examples 1

Examples 2

			References

			Olson, A.T. (1975) Mathematics Through Paper Folding. Reston, Va.: National Council of Teachers of Mathematics. http://www.vidyaonline.net/arvindgupta/paperfolding.pdf