Chart assignment
Charts to read and discuss
Read each chart, then answer its questions. Every chart shows its source and date; open it for a table of the numbers and the data to download.
Chart 1 of 3 · Space
How many planets outside our solar system are discovered each year?
The interactive chart needs JavaScript. The numbers are on the chart's page.
Astronomers confirmed 246 new planets around other stars in 2025. The first were found in 1992, and the count leaped in 2014 and 2016 (872 and 1,504), when NASA's Kepler team confirmed hundreds of its candidates at once. The archive counts a planet in the year its discovery was published and keeps adding late confirmations, so recent years can still rise.
Questions to discuss
- In one sentence of your own, what does this chart show?
- Find the biggest change or difference in the chart. What might explain it?
- Who collected these numbers, and how recent are they? What else would you want to know before drawing a conclusion?
Source: NASA Exoplanet Archive, Planetary Systems Composite Data (Public domain (NASA data); this research has made use of the NASA Exoplanet Archive, operated by Caltech under contract with NASA) · Data as of Dec 31, 2025
Open the chart and its numbersChart 2 of 3 · Crime
Is violent crime in the U.S. going up or down?
The interactive chart needs JavaScript. The numbers are on the chart's page.
Down, over the long run. Police reported about 329 violent crimes per 100,000 people in 2025, about 59% below the 1991 peak of about 798, and the lowest since at least 1985. The rate rose in 2020 and 2022, then fell in 2023, 2024 and 2025. In 2021 the FBI stopped taking its old summary reports and accepted only its newer, more detailed system (NIBRS); many police departments hadn't switched yet, so agencies covering only about 77% of Americans reported, against 88 to 98% in other years, and 2021's number is less certain. Rates count only the agencies that reported, so they differ a little from the FBI's national estimates, and the FBI widened its definition of rape in 2013.
How to read this chart
Each point is the number of violent crimes police reported for every 100,000 Americans that year. The line starts at zero, so its height shows the true size. In 2021 the FBI changed how it collects reports and fewer police departments sent numbers, so that year is less certain than the others.
Questions to discuss
- Find the year with the highest rate. About how much lower is the rate in the latest year?
- Many people say they think crime is rising. How could that belief and this chart both seem true to different people?
- Why might a change in how crimes are counted, like the one in 2021, make one year hard to compare with the rest?
Source: FBI Crime Data Explorer, Uniform Crime Reporting Program (Public domain (U.S. government work); source FBI Uniform Crime Reporting Program) · Data as of Dec 31, 2025
Open the chart and its numbersChart 3 of 3 · World
How has the world's population grown since 1960?
The interactive chart needs JavaScript. The numbers are on the chart's page.
The world had 8.22 billion people in 2025, about 2.7 times the 3.02 billion of 1960. It passed 8 billion in 2023. Figures are mid-year estimates from the United Nations, which revises them as new censuses come in.
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
- Judging from the chart, about how many years did it take the world to add its most recent billion people?
- Is the line getting steeper or flatter in recent years? What does that tell you about the growth rate?
- These numbers are estimates that the UN revises. Why is it hard to count every person on Earth?
Source: World Bank, World Development Indicators: Population, total (CC BY 4.0 (credit the World Bank)) · Data as of Dec 31, 2025
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