Adding and Subtracting Fractions
Use the sliders below to perform addition and subtraction of fractions
Megan Yanes, Created with GeoGebra
Move the red sliders to show 1/2. Move the blue sliders to show 2/5. Now move the blue point to the left so that the two squares coincide.
1. How many of the small congruent rectangles are red? (Hint: the purple ones count too)
2. How many are blue? (Same hint as above)
3. How many are there total? (Shaded and unshaded)
4. How do the answers to questions 1-3 relate to the sum of these two fractions?
5. How many red, non-purple rectangles are there?
6. How many blue, non-purple rectangles are there?
7. How do the answers to questions 6 and 7 relate to the difference of these two fractions?
8. Come up with a rule for adding fractions and a rule for subtracting tfractions using this tool.