Geometry Origami - Angelfish What shape do we begin with?

Geometry Origami - Angelfish Fold along the diagonal (colored side out), then unfold. Repeat with the other diagonal.

Geometry Origami - Angelfish Now fold the square in half so that you are creating a fold line that is parallel to two sides of the square. This time, fold colored side in. Repeat, so that you have a fold line that is parallel to the other two sides of the square.

Geometry Origami - Angelfish What shapes do you see? Can you see 4 congruent squares, each made up of 2 right triangles?

Geometry Origami - Angelfish Look at the square on the bottom right. Pick up the triangle on the top right of this square, and fold it so that it is on top of the other triangle in this square.

Geometry Origami - Angelfish Now look at the square on the bottom left. Pick up the triangle on the top left of this square, and fold it so that it is on top of the other triangle in this square.

Geometry Origami - Angelfish You should now have a right isosceles triangle. In a right triangle, the side that is opposite of the right angle is called the hypoteneuse.

Geometry Origami - Angelfish Draw a line from the right angle to the hypoteneuse so that it bisects the hypoteneuse (divides it in half). Fold and unfold along this line.

Geometry Origami - Angelfish Put a dot on the hypoteneuse about 1 cm to the left of where the fold line bisects it. Draw a line from the right angle to the dot.

Geometry Origami - Angelfish Fold the right side of the triangle (one layer) over to this second line. This new triangle becomes one of the fish fins.

Geometry Origami - Angelfish Fold the left side of the triangle (one side only) over so it is on top of the first fin.

Geometry Origami - Angelfish Flip the paper over and rotate so that it looks like a fish.