Figure 6a
Figure 6b
Figure 6c
The alphabet we use was invented by the Romans more than 2,000 years ago. The same alphabet is used for many European and other languages.
Some letters of the alphabet have several types of symmetry. Some have no symmetry at all. You can analyze the letters for symmetry.
1. Write the alphabet in plain capital letters, with no fancy doodads or decorations.
2. Imagine that you have a cutout of the letter E. Flip it upside down over an imaginary horizontal line through the middle. The letter E looks just the same as in the original position.
Make a list of all the letters of the alphabet that have this type of line symmetry. Figure 6a
3. Imagine that you have a cutout of the letter A. Flip it over an imaginary vertical line through the middle so that the point stays at the top. The letter looks exactly the same as in the original position. List all the letters of the alphabet that have this kind of line symmetry. Figure 6b
4. Imagine that you have a cutout of the letter S. Give it a half turn. The letter S looks just about the same as in the original position. List the letters of the alphabet that have this type of turn symmetry. Figure 6c
5. Some letters have more than one type of symmetry. Make a list of these letters.
6. Compare your lists. Which letters appear on two lists? On three lists?
1. Did you find any letters that have exactly two types of symmetry? There are none! Why not?
2. Some words, written in capital letters, look the same when they are flipped over.
a. Make a list of words that look the same when they are flipped over a horizontal line. Look at your list of letters with that type of symmetry to help you think of words.
b. Make a list of words that look the same when they are flipped over a vertical line.
c. Write words that look the same when you give the paper a half turn.
3. Can you find words that can be flipped over or turned to make different words?
4. The Greek, Hebrew, and Arabic languages have their own alphabets. In fact, the Romans got some of their letters from the Greeks. Look up the history of alphabets. Figure 6d
Greek letters
Figure 16d
