1. DOUBLE NUMBER LINE DIAGRAMS For example: 10 meters in 4 seconds
*Double Line Graphs are best to use when your units are not the same in your ratio.
For example: 10 meters in 4 seconds
*On a double number line diagram, if the top and bottom numbers are in the same ratio then they are located the same distance from 0 on their respective number lines.
*Once we represent 10 meters in 4 seconds below we can use multiplication and division to find other ratios that are equivalent and represent different forms of the same ratio.
*Now we use the number line relationship to come up with other ratios. An easy one is to split in half or double.
meters 5 10 20 2 4 8
seconds

2. DOUBLE NUMBER LINE DIAGRAMS
meters
2.5 5 10 15 20 1 2 4 6 8
seconds
*Let’s look at some other relationships: Let’s take 5 to 2. Knowing this, how could we determine how long it would take to go 15 meters?
Note that the distances from the respective zeros on each of the number lines is the same.
*To come up with the unit rate, we would look at the bottom unit of seconds. In order to get that to be 1 we would have to divide by two. So if we divide by two on the top and bottom we have our units for the unit rate.
*So using the double line graph we have determined that
the unit rate is 2.5 meters per second.

3. Adapted from commoncoretools.wordpress.com
Double number lines to solve problems
Driving at a constant speed, you drove 14 miles in 20 minutes. On a “double number line”, show different distances and times that would give you the same speed. Identify equivalent rates below.
Distance
0 miles
7 miles
14 miles
21 miles
28 miles
0 minutes
Time
10 minutes
20 minutes
30 minutes
40 minutes
Adapted from commoncoretools.wordpress.com