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Fraction Classroom · 2.3.0 · Student pages

Read the scale before comparing bars

Convert graph intervals into quantities before comparing categories or finding a total.

Anonymous group code: __________   Date: __________

Illustrative class votes. The vertical scale starts at zero and increases by two votes per equal interval.02468101214VotesMysterySpaceNature
Illustrative class votes. The vertical scale starts at zero and increases by two votes per equal interval.

Build the idea

model. The graph shows 6 mystery votes, 10 space votes and 14 nature votes. How many more learners chose nature than mystery?

  1. Read the category labels and the vertical-axis label before comparing the bars. Each count is a number of votes, with one vote per learner in this example.
  2. Check the labelled ticks: 0, 2, 4 and so on. Equal spaces represent equal differences of two votes, not one vote.
  3. Read the top of each bar against that scale. Mystery reaches 6 and nature reaches 14, so subtract 6 from 14.
  4. Check using the drawing: four intervals separate the bar heights, and 4 × 2 = 8 votes. Keep the unit in the final comparison.

Worked example: 8 learners. The bars differ by four scale intervals, and each interval represents two votes: 14 − 6 = 8.

Practise and explain

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

p1. Using the graph, how many votes did mystery and space receive altogether?

p2. How many more votes did nature receive than space?

p3. How many votes are represented by all three bars?

e1. A different graph uses a scale of 5 votes per interval. A bar reaches 4 intervals above zero. How many votes does it represent?

Transfer the idea

transfer. If the same 14 nature votes are redrawn using one vote per interval, does the number of votes change?