Line Plots with Fractions
A 50-minute Grade 4 lesson on making line plots of measurements in halves, quarters and eighths, and adding and subtracting fractions to answer questions about the data.
Line Plots with Fractions is a free 50-minute Grade 4 math lesson plan for Common Core standard 4.MD.B.4 — make line plots of measurements in halves, quarters and eighths, and add and subtract fractions to answer questions about them. It is timed across 5 sections, gives the exact wording to use where the wording carries the mathematics, names 3 misconceptions with the teaching move that addresses each, and ends with an exit ticket and a printable worksheet with its answer key.
- Grade:
- Grade 4
- Length:
- 50 minutes
- Standard:
- 4.MD.B.4
Grade 4 · Measurement & Data
4.MD.B.4
Make a line plot to display a data set of measurements in fractions of a unit (1/2, 1/4, 1/8). Solve problems involving addition and subtraction of fractions by using information presented in line plots.
Objective
Students will be able to make a line plot of measurements in halves, quarters and eighths of a unit and solve addition and subtraction problems using the data it shows.
Students are successful when they can
- Renames halves and quarters as eighths to place them on an eighths scale.
- Finds the difference between the longest and shortest measurement by subtracting fractions.
- Finds the total of the measurements at one value by adding a fraction as many times as there are X's.
What you need
- Rulers marked in eighths of an inch
- Ribbon or string pieces cut to lengths under 1 inch, labeled for measuring
- Blank line plot scales from 0 to 1 marked in eighths
- The printable practice sheet linked at the end of this plan
The lesson
Warm-up — name the marks
6 min- Show an inch split into eighths. Point to the second, fourth and sixth marks and ask for two names for each.
- 2/8 and 1/4; 4/8 and 1/2; 6/8 and 3/4. A line plot in eighths needs every one of those names.
Teach — plot it, then use it
15 min- Put up eight ribbon lengths in inches: 1/4, 3/8, 1/2, 3/8, 5/8, 1/2, 1/2 and 3/4.
- Draw a scale from 0 to 1 marked every eighth. Label it in eighths, and write 1/4, 1/2 and 3/4 under their eighths as well.
- Plot one X per ribbon. 1/4 goes at 2/8, not at the fourth mark. Count the X's: eight for eight ribbons.
- Ask for the difference between the longest and shortest ribbon. 3/4 − 1/4 = 2/4, which is 1/2 inch.
- Ask how long the 1/2-inch ribbons are together. Three X's: 1/2 + 1/2 + 1/2 = 3/2, which is 1 1/2 inches. The X's say how many; the scale says how long each is.
- Ask how much longer a 5/8-inch ribbon is than a 3/8-inch one. 5/8 − 3/8 = 2/8 inch. Same denominators, so count eighths.
“Each X is one measurement, and the number under it is its length. To add or subtract, rename the lengths into the same size pieces, then count the pieces.”
Guided practice — measure and ask
14 min- Pairs measure eight ribbon pieces to the nearest eighth of an inch and plot them on an eighths scale.
- They answer three questions: the difference between longest and shortest, the total length at the most common value, and how much longer one value is than another.
- For each answer, they write the fraction sentence and rename the result if it can be simplified to halves or quarters.
Independent practice
12 min- Students complete a line plot problems page.
- Look for answers in twelfths or sixteenths. They mean denominators were added, which is a fraction error rather than a line plot error.
Close
3 min- Ask how many X's would be above 7/8 if one more ribbon were measured at 7/8, and what the new longest-minus-shortest would be.
- One X, and 7/8 − 2/8 = 5/8 inch. Updating the plot in your head is the idea worth ending on.
What goes wrong, and why
Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.
Plots 1/4 at the fourth mark on an eighths scale.
Why: The denominator is being used to count marks, so a 4 in the fraction sends the X to the fourth mark whatever the scale is split into.
Fix: Rename the measurement in eighths before plotting: 1/4 = 2/8, so it goes at the second mark. Writing both names under the scale makes the match visible.
Adds 3/8 + 3/8 to get 6/16.
Why: Fractions are being added as two separate whole numbers, top with top and bottom with bottom, because that is how numbers in a row are usually combined.
Fix: Say the fraction as a count of pieces: three eighths and three eighths make six eighths. The size of the piece does not change when more pieces are added.
Answers 'how long are the 1/2-inch ribbons together' with 3, the number of X's.
Why: The question has been read as a count, which is what every earlier line plot question asked.
Fix: Ask what one X stands for — one ribbon 1/2 inch long — then add one 1/2 for each X. The answer is a length, so it needs a unit.
If they are not there yet
- Start with a scale in quarters only, so every measurement is a quarter or a half.
- Write the eighths name above every X before answering questions about it.
If they finish early
- Find the total length of all eight ribbons and write it as a mixed number.
- Make a line plot from 1 to 2 inches in eighths and answer a difference question across the whole number.
- Write a question about the plot that needs both an addition and a subtraction to answer.
Exit ticket
A line plot shows beetle lengths: two X's at 1/4 inch, one at 3/8 inch and three at 5/8 inch. What is the difference between the longest and shortest beetle? What is the total length of the 5/8-inch beetles?
What to look for: 5/8 − 2/8 = 3/8 inch, and 5/8 + 5/8 + 5/8 = 15/8 = 1 7/8 inches. An answer of 4/4 or 4/8 means 1/4 was not renamed; 3 means the X's were counted; 15/24 means denominators were added.
Printable practice for 4.MD.B.4
Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.
- Line Plots — Halves and QuartersUse the line plot to answer.
Questions about Line Plots with Fractions
How long does the Line Plots with Fractions lesson take?
50 minutes, split across 5 timed sections: warm-up 6 min, teach 15 min, guided practice 14 min, independent practice 12 min, close 3 min. The minutes are stated per section and add up to the stated length, so the plan can be cut or extended at a section boundary rather than abandoned halfway.
Which standard does Line Plots with Fractions teach?
CCSS.MATH.CONTENT.4.MD.B.4 — 4.MD.B.4, Measurement & Data for Grade 4: “Make a line plot to display a data set of measurements in fractions of a unit (1/2, 1/4, 1/8). Solve problems involving addition and subtraction of fractions by using information presented in line plots.” In plain terms, make line plots of measurements in halves, quarters and eighths, and add and subtract fractions to answer questions about them.
What do I need to teach this lesson?
Rulers marked in eighths of an inch, ribbon or string pieces cut to lengths under 1 inch, labeled for measuring, blank line plot scales from 0 to 1 marked in eighths and the printable practice sheet linked at the end of this plan. Everything listed is either ordinary classroom equipment or a free printable from this site — there is nothing to buy and nothing to prepare beyond photocopying.
What mistakes should I expect in this lesson?
Three, each a reasoning error rather than carelessness: plots 1/4 at the fourth mark on an eighths scale; adds 3/8 + 3/8 to get 6/16 and answers 'how long are the 1/2-inch ribbons together' with 3, the number of X's. The plan gives the thinking behind each one and the teaching move that addresses the thinking rather than the symptom.
How do I know whether the lesson worked?
The exit ticket asks: “A line plot shows beetle lengths: two X's at 1/4 inch, one at 3/8 inch and three at 5/8 inch. What is the difference between the longest and shortest beetle? What is the total length of the 5/8-inch beetles?.” 5/8 − 2/8 = 3/8 inch, and 5/8 + 5/8 + 5/8 = 15/8 = 1 7/8 inches. An answer of 4/4 or 4/8 means 1/4 was not renamed; 3 means the X's were counted; 15/24 means denominators were added. That tells you whether the class needs a reteach or a thirty-second conversation before you plan tomorrow.
Is there a worksheet to go with Line Plots with Fractions?
Yes — 1 printable 4.MD.B.4 worksheet, linked at the end of the plan and free like the rest of the site. Each one comes with an answer key and 25 versions, so the practice after the lesson can be a different paper on every desk.
Is Line Plots with Fractions free to use?
Yes. The plan, its printables and their answer keys are free to read, print and photocopy for your own class, with no account and no email capture. It was last reviewed on October 22, 2026. Please do not resell it or republish it as your own.
Last reviewed 2026-10-22. Aligned to 4.MD.B.4 of the Common Core State Standards for Mathematics.