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Fraction Classroom · 2.4.0 · Student pages

Count every ribbon in a fraction line plot

Turn repeated measurement marks into a usable stock record, then check both the number of pieces and their combined length.

Anonymous group code: __________   Date: __________

Ribbon lengths in metres. Each cross represents one piece; repeated crosses must each contribute their length to the inventory.01/4××1/2×3/4××1
Ribbon lengths in metres. Each cross represents one piece; repeated crosses must each contribute their length to the inventory.

Build the idea

model. The line plot represents five ribbon pieces. What is their combined length?

  1. Read the horizontal labels as lengths in metres. Each cross means one piece at that length, not one metre of ribbon.
  2. Write one measurement for every cross. Preserve both quarter-metre pieces and both three-quarter-metre pieces; repeated values still represent different objects.
  3. Rename the half metre as two quarters and add all ten quarter units. Four quarters make a metre, so ten quarters make 2 1/2 metres.
  4. Check two totals separately: there are five pieces and 2 1/2 metres. A total of three lengths would signal that repeated measurements were omitted.

Worked example: 2 1/2 metres: 1/4 + 1/4 + 1/2 + 3/4 + 3/4 = 10/4. Each mark contributes a separate measured piece.

Practise and explain

Try p1–p3 with a partner. Use a drawing and label your units. Try e1 independently before comparing responses.

p1. For the displayed plot, how many ribbon pieces are there? Enter the count.

p2. What is the total length in metres of the two 3/4-metre pieces?

p3. Using the plot, find the difference in metres between the longest and shortest piece.

e1. A new stock has three 1/4-metre pieces and one 1/2-metre piece. Draw its line plot and enter the combined length in metres.

Transfer the idea

transfer. Two stock boxes contain the same total ribbon length. Must their line plots be identical? Give a counterexample.