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Year 3 Maths Statistics & Probability

Data and Bar Graphs

Bar graphs display data using rectangular bars. The length or height of each bar shows the quantity. They make it easy to compare data.

Parts of a Bar Graph

  • Title: names what the graph shows
  • x-axis: the horizontal line (categories)
  • y-axis: the vertical line (numbers/scale)
  • Bars: rectangles showing the data value
  • Scale: equal intervals on the y-axis

Reading Bar Graphs

To read a bar graph:

  1. Read the title to know what it shows
  2. Look at the scale (y-axis) carefully
  3. Find the top of the bar
  4. Read across to the y-axis to find the value

Interpreting Data

After reading a graph, you can answer questions like:

  • Which category has the most/least?
  • How many more/fewer?
  • What is the total?

Scales and Intervals

The scale must go up in equal steps. Common scales: count by 1s, 2s, 5s, or 10s. Always check what each line on the scale means before reading the bars.

Pets Owned by Year 3 Students

Number of students who own each type of pet

10 8 6 4 2 0
Dog 8
Cat 6
Fish 3
Bird 10
Rabbit 2

Bird is most popular (10). Rabbit is least popular (2). Total pets = 8 + 6 + 3 + 10 + 2 = 29.

Key Vocabulary

bar graph — a graph using rectangular bars to compare data categories
scale — the numbered axis showing how much each division represents
category — a group of things being counted (e.g., types of pets)
interval — the equal gap between numbers on the scale (e.g., 0, 2, 4, 6...)

Knowledge Check

Question 1

Using the Pets graph above, how many more students own a Dog than a Fish?

Question 2

What is the most important thing to check before reading a bar graph?

Question 3

In the pets graph, what is the total number of students who own a cat OR a bird?

Question 4

A bar graph has a scale that goes 0, 5, 10, 15, 20. The "Summer" bar reaches exactly halfway between 10 and 15. What value does this bar represent?

Lesson Summary