Predict
Is your arm span longer or shorter than you are tall? Students record a hypothesis and guess which shape the class will be.
20 min · Warm-upGeogWeb ProjectGrades 4–83–5 class periodsMath · Geography · Data
How Square Are You?
Students measure their height and their wingspan, then find out whether they're a square, a tall rectangle or a wide one. Every class adds real data to a shared map, so students can compare themselves with kids in other states and with pro athletes in other cities.
Edition 2026-27 · Free for ClassJax teachers
The big idea
One ratio. Every body. Real data.
Leonardo da Vinci's Vitruvian Man suggests your arm span equals your height, a perfect square. Is that true for your class? For kids in Alaska and Florida? For a 7-foot center? Students collect the numbers, do the math and find out.
Squareness=wingspan
height
height
Tall rectangle
Height is longer
ratio below 0.98
Square
About equal
ratio 0.98–1.02
Wide rectangle
Wingspan is longer
ratio above 1.02
Activities
Five activities, one investigation
Run them in order over a week, or pick the ones that fit. The lesson, slides and worksheet for each are ready in the project for your planner.
Measure
Partners follow the measuring protocol: shoes off, back to the wall, fingertip to fingertip. Measure twice.
1 period · Hands-onCalculate
Divide wingspan by height, classify each shape and build a class dot plot. Who is the squarest? What is typical?
1 period · RatiosCompare with the pros
Look up real NBA measurements for players in two other cities. Where are those cities? Who is more square?
1 period · ResearchMap & share
Submit class results to the shared map, chart your class against schools across the country and write up findings.
1–2 periods · GeographyExtensions:Does squareness change with age?Swimmers vs. basketball playersMap the distance to your comparison citiesWrite a data-journalist news story
Who's measuring
Classes across the map
Every class that submits data becomes a dot on this map, colored by the shape of the class. Only class averages are public, never student names. The first edition's map fills in this year — your class can be one of the first dots.
Tall-rectangle classSquare classWide-rectangle class
How it works for teachers
Join, teach, submit, share.
- 1Join the project.
Pick a class from your ClassJax account. Joining takes two minutes and is free.
- 2Teach it your way.
Slides, worksheets and the measuring protocol are ready. Add the activities to your planner on the dates that fit.
- 3Collect class data.
Students enter measurements with anonymous codes. Ratios and shapes calculate automatically.
- 4Share what you found.
Your class joins the shared map, and students chart their class against schools across the country.
Standards alignment
6.RP.A.1Understand the concept of a ratio and use ratio language.6.RP.A.3Use ratio and rate reasoning to solve real-world problems.6.SP.B.4Display numerical data in plots on a number line.8.SP.A.1Construct and interpret scatter plots for bivariate data.
Student privacy built in
Students are entered as codes (S-01, S-02…). Shared data shows class averages, city and grade only.
Put your class on the map.
Join in two minutes. Your students' data joins classes from coast to coast.