# Lesson 3: Polygons and Parameters - Instructor's Notes

This page contains some tips and suggestions for the instructor when
presenting lesson 3.

## Lesson Goals

The goal of this lesson is for the children to:

- Learn how to create procedures that take parameters.
- Learn why parameters are useful.
- Learn about regular polygons.

## Lesson 2 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?
- How do you define a procedure in Logo?
- What is the procedure for drawing a square?
- What is the procedure for drawing a triangle?
- What is the procedure for drawing a squiral (the twisty square-spiral)?

## Formal Presentation

The "big idea" in this lesson is that procedures can take parameters
and that the parameter can change what the procedure does in useful ways.

Ask the question "what is the procedure for drawing a square" and write
the answer on the blackboard.
Now ask "what is the procedure for drawing a triangle" and write the answer
on the blackboard.
Do the same thing for a pentagon and a hexagon (you may have to tell the
children what those shapes are).

## At The Computer

Once all the procedures are on the blackboard, ask the children
if they see a pattern. Then show them how to make a single routine
that does all of those shapes (and others).
Once you have defined the routine, let the children enter it
into the computer and try different numbers.
Ask what happens when the number is smaller than 3.
Ask what happens when the number gets very large.

Finally, challenge the children to generalize the program again so that it
can draw polygons of different sizes.