As a turtle makes a 3D cube as moving forward in a virtual LEGO contest, turtle strap
applies this idea to the 2D plane. We introduced symbol ‘m’ that makes a square and symbols ‘o,
O’ that make a regular triangle. Here, small letter ‘o’ and capital letter ‘O’ are used for 60-degree
counter-clockwise rotation and 60-degree clockwise rotation respectively. That is, the symbol ‘m’
is used to make a straight-line route and ‘o and O’ are used to make changes in direction. The
symbols ‘o and O’ are to rotate 60 degree to make a regular triangle, but the symbol ‘rrv’ including
a variable can be used to adjust a rotation angle. By putting (rrv=‘a’) before o or O symbol,
students can define a rotation angle in ‘a’ (See Figure 8).