Folding Fractions
Supplies Needed:
20 sheets of Blank Paper size: 8 1/2×11
(for approximately 20 students)
Instructions:
1. Break class into 5 groups of 4. Each group has 4 sheets of blank paper.
2. Showing instruction, fold the bottom of the sheet up and to the left creating a right triangle. 3. Cut / tear the top of the folded left over top, removing the top, leaving a perfect square with a fold in it (looking like 2 triangles).
3. Write on each triangle 1/2 and 2/2, denoting the two fractions.
4. With the second sheet of paper, repeat instructions No. 2. This time folding the triangle in the opposite direction. Now there ought to be 4 folds / 4 triangles. Write on each triangle 1/4, 2/4, 3/4, 4/4, denoting the 4 fractions.
5. With the third sheet of paper, repeat instruction No. 2 again. This time folding the paper 3 times. This time there ought to be 8 folds / 8 triangles. Write on each triangle 1/8, 2/8, 3/8, 4/8, 5/8, 6/8, 7/8, 8/8, denoting the 8 fractions.
6. With the fourth sheet of paper, repeat Instruction number 2 again. This time folding the set of triangle 4 times. This time there ought to be 19 folds / 16 triangles. Write on each triangle 1/16, 2/16, 3/16, 4/16, 5/16, 6/16, …etc….up to 16/16, denoting the 16 fractions.
7. Explain that when added each group together, the total equals to the whole number 1.
Question – What is the Lowest Common Denominator?
Check out some of our other Math Games:
http://math-lessons.ca/fraction-games-activities/.
Harmony occurs in music when two pitches vibrate at frequencies in small integer ratios. Long ago, Greek people realized the concept of harmony occurred when sounds and frequencies are in rational proportion. i.e., One Octave is equal to when the frequency is doubled, and a tripling of frequency brings the key One Octave higher, and is called a perfect fifth. Though not knowing this in relation to “frequency”, ancient Greeks knew this in relation to lengths of vibrating strings; http://www.math.uwaterloo.ca/~mrubinst/tuning/12.html (Why 12 Notes to The Octave?)
The most common conception of the chromatic scale before the 13th century was the Pythagorean chromatic scale. Due to a different tuning technique, the twelve semitones in this scale have two slightly different sizes. (En. Wikipedia. org/wiki/Chromatic_scale) Thus, the scale is not perfectly symmetric. http://strathmaths.wordpress.com/2012/02/22/tipping-the-scales-some-of-the-mathematics-behind-music/. Pythagoras, 13thC Greek mathematician, was famous in geometry for the Pythagorean theorem (en. Wikipedia. org / wiki/Pythagoras). The theorem states that in a right-angled triangle, the area of the square on the hypotenuse (the side opposite the right angle) is equal to the sum of the areas of the squares of the other two sides—that is, a^2 + b^2 = c^2. Pythagoras experimented with a monochord, noticing that subdividing a vibrating string into rational proportions produced resonant sounds. When the frequency of the string is inversely proportional to its length, its other frequencies are simply whole number multiples of the fundamental. (En. Wikipedia. org/wiki/Chromatic_scale)










