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# MA 2021 Conference, Origami by Sue Pope and Tung Ken Lam

This session for the Mathematical Association Annual Conference 2021 presents some ideas for using origami for teaching and learning mathematics.

It covers some mathematics arising from a single fold, fractions, how to trisect a right angle by folding paper and therefore make an equilateral triangle, a six-pointed star, a tetrahedron and an approximation of a regular icosahedron.

Two basic folds

A valley fold is concave. A mountain fold is convex. Most origami diagrams used a dashed line for valleys. Mountain fold is usually dash-dot-dot.

One fold

Haga’s Turned Up Part (TUP)

What happens when the bottom right corner goes to the midpoint of the top edge? (Haga theorem).

Fractions

Folding in half, quarters, eighths, sixteenths, etc is easy.

How about dividing the edge of a square into thirds? Dividing a square into thirds: Here are eight methods for dividing a square into thirds. How can you prove each method works? What are the advantages and disadvantages of each method? Which methods can be generalised to oblongs and other divisions e.g. fifths and sevenths?

Crease an A4 sheet into a 4 by 4 grid.

Make a magazine box. What size paper do you need to make two smaller magazine boxes fit inside? What are the ratios of lengths, surface areas and volumes?

Dave Mitchell’s Two-way Tube – which configuration has the greater volume, or are they the same?

https://www.atm.org.uk/Shop/Learning-Mathematics-with-Origami-book-and-pdf/act0101pk

60 degree fold

Fold the lower right corner to the centre line and at the same time make the fold go through the lower left corner.