Origami Octogonal Ninja Star

Shuriken ( literally "hand hidden blade") is a traditional Japanese concealed weapon that was used for throwing, and sometimes stabbing. They are small, sharpened, hand-held blades made from a variety of everyday items, such as needles, nails, and knives, as well as coins, washers, and other flat plates of metal.

We of course are making these so called "Ninja Stars" out of paper to be "somewhat" safe. It will fly like a small frisbee.

The learning objectives are:

1. Cutting paper by creasing at desired fold, licking the edge to weaken the integrity of the paper and cutting with precision.
2. Creating a Square from a non-square rectangle.
3. Folding paper with precision (I call this process, "Fold, Hold, and Crease"); it is very normal for children with developing fine motor skills to crease before they get the fold that they desire. This takes discipline and practice.
4. Vocabulary such as square, rectangle, ratio, triangle, right isosceles triangle, parallelogram, rhombus, diamond is not a mathematical term, vertex, parallel, perpendicular, counterclockwise, polygon, hexagon, heptagon, octagon, and other mathematical terms.

We covered the following topics (see the 16 pictures and explanation, on pages 4, 5, and 6 of the Ninja Star.pdf). Also, the second pdf named Ninja Star Shapes.pdf will help the children match up the fold from each step to check their work:

· Creating the original square from a rectangular piece of paper requires that you fold the short side at a 45 degree angle down to the long side measuring the identical distance. Then we cut off the excess part of the rectangle to reveal the square (see the next page). 

· A square has dimensions in a one to one ratio. If the sides are each 8.5 inches, it has a one to one ratio.

· The next step is to cut the square in half vertically or horizontally creating two rectangles with two to one ratios.  

· The next step is to fold those rectangles in half the long way creating 4:1 ratio rectangles.

· Then we fold that in half the short way, again creating rectangles with 2:1 ratios.

· The next step is very important as it needs to be consistent. We fold the right side down and the left side up creating 45 degree rectangles.

·  When you turn over the pieces, you should see two squares on the ends of each piece. The next step is to fold those squares in half diagonally to create the picture numbered 10 and 11 in the pdf.

·   Finally, you fold each of those shapes (called isosceles right triangles) over to complete the parallelogram.

• Next, you place the parallelograms face up and perpendicular to each other. One on top of the other. Perpendicular means in a 90-degree angle or like a cross.

• Then you begin folding down the isosceles right triangles down on top of the other flaps and turn counterclockwise before each fold.

• The last fold is the most difficult as you fold the triangle down over one flap and under the other into a pocket to lock the star.

• Now you are ready to fly your star.

• REMEMBER NOT TO THROW IT TOWARDS ANOTHER PERSON AS IT CAN HURT.

It is tremendous fun to create a target such as plastic cups shaped as a pyramid to knock down with your star.