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 · Income tax
What is the average income on tax returns in your ZIP code?
The interactive chart needs JavaScript. The numbers are on the chart's page.
Type any ZIP code to see the average income on the tax returns filed from it in tax year 2023, next to its state's and the U.S. average of $96,717. ZIP code 20001 in Washington, D.C., shown first, averaged $126,264. In tax year 2022, across the 27,588 ZIP codes in the data, half averaged less than about $68,300, and the highest was Fisher Island, Florida (33109), at $4.4 million on 400 returns. Income here is adjusted gross income, the income on a tax return after a few adjustments; an average can be pulled far up by a few very large incomes, and one return can cover a married couple. The IRS leaves out ZIP codes with fewer than 100 returns, single buildings and nonresidential ZIP codes, and returns with negative income. Tax year 2023 is the newest year the IRS has published by ZIP code.
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: IRS Statistics of Income, individual income tax ZIP code data (Public domain (U.S. government work)) · Data as of Dec 31, 2023
Open the chart and its numbersChart 2 of 2 · 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.