Lesson 2: Basic Loops - Instructor's Notes

This page contains some tips and suggestions for the instructor when presenting lesson 2.

Lesson Goals

The goal of this lesson is for the children to:

  1. Understand how REPEAT ... REPCOUNT can be used to make various spiral shapes.
  2. See how a simple idea can offer a lot of room for exploration.
  3. Review and solidify their understanding of angles.

This lesson only contains one new idea, so it provides a good opportunity to review the material covered in the first lesson.

Lesson 1 Review

Ask the following questions to remind the children of what the learned in the previous lesson.

Formal Presentation

The "big idea" in this lesson is the repeat counters. The power of the repeat counter may be lost of you just let the children type in programs, so it is helpful to work through one example on the blackboard beforehand.

Ask the question "what happens if I take one step, turn right, take two steps, turn right, take three steps, turn right, and so on?" Then draw the pattern on the blackboard, one command at a time. It is important that children see how the "REPCOUNT" leads to a spiral effect.

For the older kids, you can ask them to create new sequences by doing some math on the basic sequence of <1, 2, 3, 4, 5, 6, ...>. Ask how you could make the spiral wider (by multiplying REPCOUNT by some number). Ask how you could remove the middle part of the spiral (by adding a number to REPCOUNT). Ask how you could spiral inward, instead of outward--that is, how you could count backward (by subtracting REPCOUNT from a number).

At The Computer

The first program that the children should enter is:

REPEAT 100 [ FORWARD REPCOUNT * 2  RIGHT 90 ]

Ask them what would happen if you changed the turn angle by just a little bit, for example, just adding one. (Let them try it). Then ask what would happen if you subtracted one, instead of adding one. Then let them explore different number.