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 · Clinical trials
Which diseases get the most clinical trials?
The interactive chart needs JavaScript. The numbers are on the chart's page.
About 85,000 clinical trials registered on ClinicalTrials.gov as of November 2026 study cancer and other tumors, more than any other disease group; brain and nerve diseases come next with about 57,000. Groups are the National Library of Medicine's disease categories, and a trial counts in every group its conditions fall under, so the bars add up to more than the total.
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: ClinicalTrials.gov (U.S. National Library of Medicine), counted with its API v2 (Public domain (U.S. government work); source National Library of Medicine) · Data as of Nov 4, 2026
Open the chart and its numbersChart 2 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
Open the chart and its numbersChart 3 of 3 · Wealth
How is U.S. household wealth divided?
The interactive chart needs JavaScript. The numbers are on the chart's page.
At the end of June 2026, the wealthiest 1% of U.S. households held 32.5% of all household wealth, the next 9% held 36.4%, the next 40% held 28.8% and the bottom 50% held 2.3%. In 1989 the shares were 22.8%, 38.0%, 35.7% and 3.5%. Wealth here is net worth: what households own (homes, stocks and mutual funds, pensions and retirement accounts, private businesses, cars and other belongings, bank deposits) minus what they owe (mortgages, credit cards, student and car loans). The Fed estimates each quarter by combining its Financial Accounts with its Survey of Consumer Finances, taken every three years, so the newest quarters are estimates that get revised.
How to read this chart
Each bar is one group of U.S. households' share of all household wealth, so the four bars add up to 100%. The groups are different sizes: the top 1% is one household in every hundred, while the bottom 50% is half of all households. Compare each group's share of wealth with its share of households.
Questions to discuss
- Which group holds the largest share of wealth? Is it the group with the most households?
- If wealth were split evenly, what share would the bottom 50% hold? How far is the chart from that?
- The takeaway gives the 1989 shares too. Which groups gained a share since then, and which lost one?
Source: Federal Reserve Board, Distributional Financial Accounts (Public domain (Federal Reserve Board; cite the Board as the source)) · Data as of Jun 30, 2026
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