### TurtleArt: 3 Shapes

A fun TurtleArt challenge is to create three shapes:

• Square
• Circle
• Triangle

#### Square

Let us start with the square. As with many TurtleArt procedures, there is more than one way to create a square.

Some students put together a forward box and a left box and clicked it enough times to make a square. How many times did they have to click these boxes to make a square?

Some students figured out that if they put enough forward and right (or left) blocks together they could make a square and only have to click once on the stack of blocks.

A really elegant way of making a square is to use the Repeat box. How many sides does a square have? This would be the minimum number of times you would have to repeat a forward and a right (or left) command to make a square.

A square has four sides, so you would repeat four times.

#### Circle

Next, onto the circle. Some students found the Arc block. The default settings are an angle of 180 and a radius of 100. Clicking it once gives us half a circle.

Clicking it twice gives us a whole circle.

What could you change to make it so you had to click only once on the Arc block to make a circle?

Here is another way to make a circle.

Why does the turtle repeat these commands 360 times?

#### Triangle

The third shape was the most vexing for students. Some were able to make a triangle but only by picking up the turtle. It would be better to write a procedure that you could click to have the turtle draw a triangle without needing to reposition the turtle.

There are a few rules about triangles that are good to know.

• If you have three equal sides, you will have three equal angles
• If you have two equal sides, you will have two equal angles
• If you have no equal sides, none of the angles will be equal
• The sum of the three angles in a triangle equals 180 degrees
Muller, Jim. The Great Logo Adventure: Discovering Logo on and off the computer. 2nd printing. Madison, AL: Doone Publications, 1998. Print.

Knowing these rules makes drawing triangles easy.

Three equal sides:

Two equal sides:

No equal sides: