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. For example, from a line plot find and interpret the difference in length between the longest and shortest specimens in an insect collection.
Official wording from the Common Core State Standards for Mathematics (Β© 2010 National Governors Association Center for Best Practices and Council of Chief State School Officers). View on thecorestandards.org
A line plot shows each data value as an X (or dot) above a number line. In fourth grade, the data are measurements in fractions of a unit, such as the lengths of pencils measured to the nearest 1/4 inch or the heights of seedlings to the nearest 1/8 inch. Students build the scale with fractional tick marks, place each measurement, and then use the plot to answer questions.
The questions call for adding and subtracting fractions with like denominators, which ties this standard to 4.NF.B.3. A classic example is finding the difference in length between the longest and shortest insects in a collection. Students might also find the total length of all items measuring 3/8 inch, or how many measurements are greater than 1/2. Because the scale may use halves, quarters and eighths together, students often rename values to a common unit like eighths before calculating. Reading a line plot correctly, including counting stacked marks, is a key part of the skill.
Students space 1/8, 1/4 and 1/2 evenly as if they were consecutive. Marking every eighth first and then labeling quarters and halves keeps the scale accurate.
When asked how many items measure 3/4, students count one for the column instead of every stacked X. Encourage touching each mark.
Subtracting 1/4 from 7/8 as 6/4 shows the units were mixed. Renaming 1/4 as 2/8 gives 5/8.
A line plot shows beetle lengths: 1/4 inch (2 beetles), 3/8 inch (3 beetles), 5/8 inch (1 beetle) and 7/8 inch (2 beetles). What is the difference between the longest and shortest beetle?
Answer: The longest beetle is 5/8 inch longer than the shortest.
Let students collect their own data: measure the length of fingers, leaves or pencils to the nearest quarter or eighth inch. Building the line plot from real measurements makes the scale meaningful.
Assessment items often give a finished line plot and ask a two-step fraction question. Practice reading values carefully and writing an equation for the question before solving.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: 4/8 (also accepted: 1/2)
7/8 - 3/8 = 4/8 inch, which is the same as 1/2 inch.
Answer: 9/4 (also accepted: 2 1/4)
3/4 + 3/4 + 3/4 = 9/4, which is 2 1/4.
Answer: B) 0, 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, 1
In eighths the order is 0, 1, 2, 3, 4, 5, 6, 7, 8 eighths, and 2/8 = 1/4, 4/8 = 1/2, 6/8 = 3/4.
Answer: C) 7
Count every mark: 2 + 4 + 1 = 7 measurements.
Answer: 2 2/4 (also accepted: 2 1/2, 2.5)
Subtract the wholes: 6 - 4 = 2. Subtract the fractions: 3/4 - 1/4 = 2/4. The difference is 2 2/4 = 2 1/2 inches.
A full lesson with slides, activities and an exit ticket on line plots of fractional measurements, pitched to grade 4 and editable in PowerPoint or Google Slides.
Make a lesson βA printable, differentiated worksheet on 4.MD.B.4 with an answer key, ready in about a minute.
Make a worksheet βTurn line plots of fractional measurements into a quiz students answer online that marks itself, with a class summary for you.
Build a test βHalves, quarters and eighths of a unit, so students can practice adding and subtracting fractions with like denominators.
Fifth grade (5.MD.B.2) uses all four operations with the data, such as finding the amount each container would hold if a total were shared equally.