Charts to read and discuss

Questions to discuss

1. In one sentence of your own, what does this chart show?
2. Find the biggest change or difference in the chart. What might explain it?
3. Who collected these numbers, and how recent are they? What else would you want to know before drawing a conclusion?

How to read this chart

Each point is the number of people alive in the world in the middle of that year, estimated by the United Nations. The axis starts at zero, so the height of the line shows the true size. Look at how steep the line is to see how fast the population grew.

Questions to discuss

1. Judging from the chart, about how many years did it take the world to add its most recent billion people?
2. Is the line getting steeper or flatter in recent years? What does that tell you about the growth rate?
3. These numbers are estimates that the UN revises. Why is it hard to count every person on Earth?

How to read this chart

Each point is the number of people killed in traffic crashes for every 100 million miles Americans drove that year. Dividing by miles driven turns a count into a rate, so years when people drove more or less can be compared fairly.

Questions to discuss

1. About what fraction of the 1980 rate is the rate in the latest year?
2. In 2020 people drove less, but the rate went up. What could explain that?
3. Why is deaths per mile a fairer way to compare years than the total number of deaths?