Course:Harris, Fall 07: Diary Week 2

(short week)

Wed:

• collected Polygon Exercises
• class finished up last week's Tessellations Exploration (~20 mintues), turned it in
• took first look at Kali (~20 minutes), considering what different types of symmetry were being created
• started working on Symmetry of Stars Exploration, but didn't finish

Fri:

• spent most of the class (~30 min) delving into #3 of last week's Exercises:
  • why triangle angle-sum is 180 (opposite interior angles)
  • why quadrilateral angle-sum is 360 (two interior triangles)
    • why one has to be careful with diagonals for non-convex quadrilaterals
  • why, in a quadrilateral, opposite angles being congruent implies opposites are parallel
    • need to get to opposite interior angles
    • that means need to show adjacent angles add to 180
    • how to get to that by using quadrilateral angle-sum is 360
• class finished up Symmetry of Stars Exploration
• just began to discuss Rotational and Reflectional Symmetries in Escher Exploration