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Fun with Polygons (Programming Class 9)

who: Baan Pathomtham Grade 5
when: Monday morning
where: at school

**Reviewing last week assignment**

As usual, I started with homework review which is to draw a scary ghost with a bonus point if they can make their ghosts disappear and reappear. Turned out to be a nice segue into my main agenda this week which is to review the for loop and a little bit of geometry. I pointed out that their codes could be shorten by using for loops.

**Fun with Polygons**

Although my main goal for this session was to review for loops, I wanted to throw in a bit of geometry review (have been noticing that the kids were using too much trial and error strategy when they drew non-quadrilateral shapes). The structure of this session was I asked them to draw various polygons using for loops:
- we started off with the basics: square and equilateral triangle
- Then I asked them to generalize their program to make any polygon. This requires two things:
1) Understand how to change the number of iterations in the for loops
2) Recognize that the angle for the turtle to turn is 360/n where n is the sides of the polygon. I showed them Josh's little program to illustrate this fact (http://jgplay.pencilcode.net/edit/explainer/extAngles)
- Next I asked them to use for loops to draw a rectangle. Here they have to recognize that the input into for loops can be other things than a sequence of natural numbers.

**Things to Note (Debate?) for Future Lessons**
Up til now, our main teaching approach has been to show them codes, run it to see what happens, and then ask the students to extend the codes. While this show-don't-tell approach is great at stimulating their creativity and interest in class, my opinion is that our G5 students need a bit more explicit blackboard instructions to get a strong grasp of the concept. Thus, I think we need a balance between learning by exploration vs. with explicit instructions.
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