Grade 4 · Unit 9: Data representation and interpretation

Displaying and interpreting data

Bar graphs, line graphs and the mean.

Temperature rises in the morning and falls at night.

Temperature through the day

Weather stations record temperature every hour. A line graph shows how it changes. We can read values between the points.

Line graphs

The temperature rises until about 15:00. Then it falls in the evening. Line graphs work best for continuous change over time.

Averages

Mode: the most common value = 45. Mean: (45 + 30 + 45 + 60 + 20) ÷ 5 = 200 ÷ 5 = 40. Range: 60 − 20 = 40.

Drawing conclusions

The mean tells a typical score. The range tells how spread out the scores are. Use both to describe data.

Can we join the dots?

For temperature over a day, points between the hours have meaning – join them with a line. For heights of different children, there is nothing “between Ali and Bina” – use bars. Changing the scale on the vertical axis can make differences look big or small.

Testing a hypothesis

A hypothesis is an idea you can test, such as “Taller children jump further.” Collect data, draw a graph, and see if the data agrees. Statistics are used everywhere: weather, cricket, health and elections.

What I learnt