Regular Polygons

Age
6-9.

Materials

 * Reading labels: "pentagon", "hexagon", "octagon", "nonagon", "decagon"
 * A series of ten cards: "&lt;/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 (&lt;).
 * 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 &lt;.
 * 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 &lt;.
 * 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.