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 2 · Earthquakes
How many earthquakes are recorded worldwide each year?
The interactive chart needs JavaScript. The numbers are on the chart's page.
Seismographs recorded 8,556 earthquakes of magnitude 4.5 or more around the world in 2025, 2.9 times the 2,987 of 1973, when the U.S. Geological Survey's modern catalog begins. Much of that rise comes from more and better sensors catching smaller quakes, not from more earthquakes: the count of magnitude 6 or more stayed between about 80 and 210 a year from 1973 to 2025.
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: 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 2 · Income and poverty
What is the typical household income in each state?
The interactive chart needs JavaScript. The numbers are on the chart's page.
In the Census Bureau's 5-year survey ending in 2024, the typical household in District of Columbia earned $109,870 a year, the most, followed by Massachusetts ($103,960) and Maryland ($103,678). Mississippi was lowest at $56,447, and the U.S. median was $80,734. These are 5-year estimates in 2024 dollars, each with a margin of error.
How to read this chart
Each bar is the median household income in a state: half of households earn more and half earn less. The dashed line is the whole U.S., for comparison. These are survey estimates, and each has a margin of error: the true value is likely within that range, so states with overlapping ranges may not really differ.
Questions to discuss
- Find your state. Is it above or below the U.S. median, and by about how much?
- Why do statisticians often use the median instead of the average (mean) for income?
- Housing and groceries cost more in some states. What would you need to know to compare what these incomes can buy?
Source: U.S. Census Bureau, American Community Survey 5-year estimates (Public domain (U.S. government work). This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.) · Data as of Dec 31, 2024
Open the chart and its numbersTeachers: make your own chart assignment, or change this one. Free, no account needed.