# for Teachers

Scratch for Teaching and Assessing Geometry Concepts

Scratch is fun. More important, students find it easy to code in Scratch, and learning or applying math concepts can happen routinely and seamlessly.

Scratch Exercise #1: Code for a … Polygon?

What do you think this code will draw? A perfect exercise for 7th or 8th grade geometry class when discussing circles and/or exterior angles of a polygon. It assumes that students are familiar with the role of a variable and how to construct it.

Ideas/Questions to explore:

The exterior angles of  a polygon add to 360 degrees. If we work with a regular polygon, each exterior angle is given by 360 divided by the number of sides.

But what does a polygon with 100 (relatively small) sides look like? Scratch Exercise #2: Code for a Spiral

The goal of this exercise is for students to write the code that will produce a spiral. It assumes that students are familiar with the role of a variable and how to construct it. (One could also easily reverse the assignment to ask students to guess what the code will draw.)

Discuss with students the definition/shape of a spiral, ie a curve winding around a center and gradually receding from or approaching it.

Ideas/Questions to explore:

How would the use of a variable make the code more efficient?

What should the variable represent?

What should be the starting value of the variable?

What increment should the variable change by?

What angle measure would best reflect the turn of the spiral curve? Spiral Spin-off: Can you use the code from Code for a Spiral above to get the following shape? Ideas/Questions to explore:

How would you change the role of the variable?

What should be the starting value of the variable?

What increment should the variable change by?

What should be the measure of the angles?

More important, explore! See if slightly different variable and angle measure can yield similar results. 