# 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:

- Understand how REPEAT ... REPCOUNT can be used to make various spiral shapes.
- See how a simple idea can offer a lot of room for exploration.
- 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.

- What did you learn in the previous lesson?
- What command moves the turtle forward?
- What command moves the turtle backward?
- What command turns the turtle to its right?
- What command turns the turtle to its left?
- How many degrees do you turn to make a corner of square?
- How do you repeat the same command over and over again?
- What happens if you give FORWARD a really big number?
- What happens if you give RIGHT a really big number (trick question!)?
- How do you teach the turtle a new command?
- If you have a bunch of commands that draws a shapes, how can you
change those commands to make it draw the same shape twice is large?

## 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.