Regular Polygons

Age

6-9.

Materials

• Reading labels: "pentagon", "hexagon", "octagon", "nonagon", "decagon"
•  A series of ten cards: "</angulus", "3/tria-", "4/quatuor-", "5/pente", "6/hex-", "7/hepta-", "8/okto-", "9/nonus or ennea", "10/deca-", "n/polys-"
• Drawer 3
• The frame and inset of triangle and square from the presentation tray.
  

Presentation

1. Position the two extra insets to the left of the drawer in line with the top row.
2. Isolate the triangle.
3. Invite the child to identify an angle.
4. Identify one on the square also.
5. Isolate the decagon and invite the child to identify an angle.
6. Feel it and compare it to the triangle and square.
7. This angle is less sharp than the angles f the triangle.
8. Present the symbol card which represents angle (<).
9. Identify the angles on the triangle and count them.
10. Place the 3 card and the angle card side by side over the inset frame.
11. Continue with each of the other figures, counting the angles, and placing the corresponding numeral card with the angle card.
12. Since there is only one angle card, it floats from one inset to the next as needed.
13. Isolate the triangle inset and the two cards 3 <.
14. The child identifies the figure and gives the meaning of its name.
15. Then turn over the cards reading the Latin words which were made into a compound word to get triangle.
16. Return the inset to its frame with its number card.
17. Isolate the square inset and cards: 4 <.
18. Turn over the cards to find that 4 angles was quatuor angulus, from which our word quadrangle was derived.
19. Go on naming the other figures in this way using the Greek word for angle - gonia. Note: nonus - ninth, and ennea - nine.
20. After ten we have no more figures in our materials.
21. Imagine a figure with any number of sides... 15, 20, 100, any figure with more than three sides.
22. We can indicate this number by n.
23. Bring out the card and place next to it the angle sign.
24. Turn over the cards: polys - many, and gonia - angle.
25. Any figure that has more than three sides is a polygon.
26. All of these figures we've examined up to now are polygons.
27. Beginning with the triangle turn all of the figures in their frames to show that the sides and angles are equal.
28. All of these are "regular polygons".
29. Name each figure: regular triangle is an equilateral triangle; a regular quadrangle is a square; a regular pentagon; a regular hexagon... and so on.
30. Do a three-period lesson and give the reading labels.