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 · Health
How long do Americans live, and how has that changed since 1900?
The interactive chart needs JavaScript. The numbers are on the chart's page.
A baby born in the US in 2018 could expect to live 78.7 years, up from 47.3 in 1900. The sharpest drop was in 1918, to 39.1 years, during the influenza pandemic. This CDC dataset stops at 2018; later NCHS reports put life expectancy at 78.4 years in 2023 and 79.0 in 2024, after a fall during the COVID-19 pandemic.
How to read this chart
Each point is how long a baby born in that year could expect to live, if death rates stayed as they were that year. It is an average, so it is pulled down a lot when many babies and young people die. Hover or tap a point to read its year and value.
Questions to discuss
- Find the sharpest drop on the chart. What happened in the world that year?
- Life expectancy in 1900 was under 50. Does that mean most adults died in their 40s? What else could lower the average?
- What changes in medicine, food or public health could explain the long rise?
Source: CDC National Center for Health Statistics, Death rates and life expectancy at birth (Public domain (U.S. government work)) · Data as of Dec 31, 2018
Open the chart and its numbersChart 3 of 3 · 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 numbersTeachers: make your own chart assignment, or change this one. Free, no account needed.