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 · Air travel
What time of day are flights most likely to be delayed?
The interactive chart needs JavaScript. The numbers are on the chart's page.
In the 12 months to August 2026, 8.0% of flights scheduled to leave between 6 and 7 a.m. left 15 or more minutes late, against 35.7% of those leaving between 8 and 9 p.m. Delays build through the day as late planes make their next flights late too, so the first flight of the morning is the safest bet. Hours are local time at the departure airport.
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. Bureau of Transportation Statistics, Airline On-Time Performance (Reporting Carrier On-Time Performance, 1987–present) (Public domain (U.S. government work)) · Data as of Aug 31, 2026
Open the chart and its numbersChart 2 of 2 · Crime
Which big U.S. cities have the most violent crime?
The interactive chart needs JavaScript. The numbers are on the chart's page.
In 2025, Memphis, TN had the highest violent crime rate of the 89 biggest U.S. cities whose police reported a full year to the FBI, about 1,853 per 100,000 people, followed by Detroit, MI (1,654) and Oakland, CA (1,475). Irvine, CA (79) and Virginia Beach, VA (101) had the lowest; the U.S. rate was about 330. Violent crime is murder, rape, robbery and aggravated assault. In 2025 the police in New Orleans, Orlando and St. Petersburg, Florida, didn't report a full year of crimes, so they are left out. Each rate is per person the department serves, and a few, such as Las Vegas, Honolulu, Jacksonville and Louisville, serve their whole county. A city's rate also depends on where its borders fall, so compare cities with care.
How to read this chart
Each bar is one big city's violent crimes reported to the FBI in a year (murder, rape, robbery and aggravated assault) for every 100,000 people its police department serves. The dashed line is the rate for the whole U.S. Dividing by population makes big and small cities fair to compare, but a city's rate also depends on where its borders fall.
Questions to discuss
- Find the city with the highest rate and the one with the lowest. About how many times higher is the top rate?
- Some departments police a whole county, suburbs included. How could that change a city's rate compared with one that covers only its downtown?
- These are crimes reported to police. What kinds of crime might never show up in these numbers, and why?
Source: FBI Crime Data Explorer, Uniform Crime Reporting Program (Public domain (U.S. government work); source FBI Uniform Crime Reporting Program) · 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.