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 4 · Climate
How much has the US warmed since 1895?
The interactive chart needs JavaScript. The numbers are on the chart's page.
The contiguous US averaged 54.6°F in 2025. The warmest year since records began in 1895 was 2024, at 55.5°F. Through 2025, the dashed trend line, the straight line that best fits every year, rose about 0.18°F a decade, or 2.3°F since 1895, and warming had sped up to about 0.5°F a decade since 1970. Alaska and Hawaii aren't included.
How to read this chart
Each point is one year's average temperature across the lower 48 states, in degrees Fahrenheit. The axis doesn't start at zero, so a small rise looks steep: read the numbers on the axis, not the height of the line. The dashed line is the trend, the straight line that best fits every year; single years bounce above and below it.
Questions to discuss
- Find the warmest and coolest years on the chart. How many degrees apart are they?
- Why might one year be much cooler than the year before, even while the trend line keeps rising?
- The axis doesn't start at zero here, but bar charts always do. Why is that fair for temperatures but not for bars?
Source: NOAA National Centers for Environmental Information, Climate at a Glance (Public domain (U.S. government work)) · Data as of Dec 31, 2025
Open the chart and its numbersChart 2 of 4 · Baby names
How many babies were given your name each year since 1880?
The interactive chart needs JavaScript. The numbers are on the chart's page.
Type any name to see how many U.S. babies were given it each year since 1880, for girls or boys. Emma, shown first, went from 2,003 girls in 1880 down to 414 in 1976, then back up to a peak of 22,719 in 2003; in 2025 it was 12,754. The counts come from Social Security card applications, so the early years undercount everyone. A year with fewer than 5 babies of a name shows as 0, because Social Security leaves those names out for privacy.
How to read this chart
Each point is the number of U.S. babies given a name in one year, from Social Security card applications. Type any name to see its line, for girls or boys. These are counts, not shares, and far more babies are born today than in 1880, so a count can grow just because the country did.
Questions to discuss
- Look up your own name or a friend's. When was it most popular, and what might explain that?
- Why are counts from the 1880s lower than counts today, even for names that were very popular then?
- How could you change these counts to fairly compare a name's popularity in 1900 with today?
Source: U.S. Social Security Administration, Baby Names from Social Security Card Applications (national data) (Public domain (U.S. government work)) · Data as of Dec 31, 2025
Open the chart and its numbersChart 3 of 4 · 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 4 of 4 · Earthquakes
How much rarer is each step up in earthquake magnitude?
The interactive chart needs JavaScript. The numbers are on the chart's page.
In 2025 the world recorded 6,428 earthquakes of magnitude 4.5 to 4.9, 1,983 of magnitude 5, 129 of magnitude 6, 15 of magnitude 7 and 1 of magnitude 8 or more. Each step up in magnitude is roughly ten times rarer, and releases about 32 times more energy. Countless smaller quakes go unrecorded worldwide, so the chart starts at 4.5.
How to read this chart
Each bar counts the earthquakes recorded worldwide in one year within a range of magnitudes. The bars start at zero. Each whole step up in magnitude releases about 32 times more energy, so a magnitude 7 quake is far more than one step stronger than a 6.
Questions to discuss
- Roughly how many times more common is each band than the one above it?
- The biggest bars are hard to compare with the smallest ones on this scale. What other way could you show these numbers?
- The chart starts at magnitude 4.5. Why might smaller earthquakes around the world go uncounted?
Source: U.S. Geological Survey, ANSS Comprehensive Earthquake Catalog (ComCat) (Public domain (U.S. government work); source U.S. Geological Survey) · Data as of Dec 31, 2025
Open the chart and its numbersTeachers: make your own chart assignment, or change this one. Free, no account needed.