M3.4.5 For the adult
Direct proportion
When one amount doubles, does the other amount always double too?
What this chapter teaches
Two amounts are in direct proportion when one divided by the other is the same for every pair. On a graph this is a straight line through zero. A line that starts above zero is not direct proportion.
Three questions to ask
There is no one right wording. Listen for the idea.
- How can you test a table of values for direct proportion?
- Why is the seedling not in direct proportion to the weeks?
- What would the graph of rice and water look like if it were not in direct proportion?
After the chapter, the learner can
- Spot when two amounts grow at the same rate
- Use a table of values to solve a proportion problem
What they copy into their notebook
In direct proportion, the second amount divided by the first is the same in every row. The graph is a straight line through the origin. Test every pair, not just one.