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 · 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 numbersChart 2 of 3 · Wealth
What is the median household net worth by age?
The interactive chart needs JavaScript. The numbers are on the chart's page.
In the Federal Reserve's 2025 survey, the typical (median) household headed by someone under 35 had a net worth of $32,820, and one headed by someone 35 to 44 had $156,000. The median was $254,670 for ages 45 to 54, $411,340 for 55 to 64, $431,900 for 65 to 74 and $504,600 for 75 and over, about 15 times the under-35s'. The median is the household in the middle: half have more and half less. Averages are much higher, because a few households are very rich. Net worth is what a household owns (homes, retirement accounts, stocks, businesses, cars, bank accounts) minus what it owes (mortgages, student and car loans, credit cards). The survey is taken every three years, and figures are in dollars of the survey year. People of different ages also lived through different times, so this compares age groups, not one household's path through life.
How to read this chart
Each bar is the median net worth of households, grouped by the age of the person who heads them. Net worth is what a household owns, such as a home, savings and retirement accounts, minus what it owes, such as a mortgage or student loans. The median is the household in the middle: half have more and half have less.
Questions to discuss
- Which age group has the highest median net worth, and about how many times the under-35 group's is it?
- Why might net worth keep rising through most of a working life, and why might it fall for the oldest group?
- A few very rich households pull the average far above the median. Why is the median a better picture of a typical household?
Source: Federal Reserve Board, Survey of Consumer Finances (Public domain (Federal Reserve Board; cite the Board as the source)) · Data as of Dec 31, 2025
Open the chart and its numbersChart 3 of 3 · 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 numbersTeachers: make your own chart assignment, or change this one. Free, no account needed.