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