Measurement Line Plots
Make a line plot to display measurement data in fractions of a unit (1/2, 1/4, 1/8); solve problems involving addition and subtraction of fractions using line plot data
What a learner can do afterwards
- Create a line plot of seed growth measurements in 1/8-inch increments
- Use a line plot to find the difference between the longest and shortest specimens
- Calculate the total length of all items in a line plot by adding the fractional measurements
- Convert eighths to decimals to report a line-plot reading
- Compare fractional measurements from a line plot using common denominators or decimals
1 · Read
You know how to make a line plot with halves and quarters. Each X stands for one measurement at that exact spot. Seedling lengths can fall between whole-number marks, so plots use 1/2, 1/4, or 1/8. Eighths hide decimals. One eighth is 0.125, so multiply 0.125 by the top. Two eighths is one quarter, so 1/4 is 0.25. Four eighths is one half, so 1/2 is 0.5. Six eighths is three quarters, so 3/4 is 0.75. To compare, use decimals: 0.25 is smaller than 0.75.
The range is longest minus shortest: 7/8 inch minus 2/8 inch equals 5/8 inch for Mia's seedlings.
Mia also wants the total length of the three seedlings that measured 6/8 inch. She adds 6/8 + 6/8 + 6/8 and gets 18/8, which is the same as 2 and 2/8 inches.
Before you add or subtract fractions from a line plot, check that the bottom numbers match. If they are already eighths, just add or subtract the top numbers and keep the 8.
Two marks can use different bottoms, like 1/2 and 5/8. Rewrite 1/2 as 4/8 first. Then subtract the tops: 5/8 minus 4/8 leaves 1/8.
A line plot lines up every measurement so you can subtract for the difference and add for the total, matching denominators first and then keeping the shared one.
2 · Watch
Take it off screen
Where it sits
Where this leads
18 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.