Free classroom activity · Activity 2
Orders of
Magnitude
Explore scale one power of ten at a time, from microscopic structures to planets and stars.
Begin the journeyPrintable resources
Download the activity
Use the worksheet with students, keep the guide for lesson notes and answers, or download both in one file.
What students will learn
- Recognise one order of magnitude as a factor of ten.
- Compare quantities written in scientific notation.
- Estimate the nearest power of ten for real objects.
- Turn exponent differences into approximate multipliers.
- Connect abstract notation with physical scale.
Classroom set-up
Subjects: maths, physics, general science, astronomy and scale in biology.
Materials: one worksheet per student, pencils and one connected device per pair where available.
Students should record estimates before using the visual journey or entity links.
Interactive journey
Travel through powers of ten
Move one whole exponent at a time. Each decade contains one curated entity or an honest gap—never a borrowed neighbour.
People
Human ↗
1.75 mActual measurement 1.75 × 100 m
Nearest power 100 m
A defined adult standing 1.75 m tall with a mass of 70 kg. This is a consistent comparison specimen, not a global average or health benchmark.
Student activity
Six tasks across 19 powers of ten
Write an exponent first. Then use the links or interactive journey to check your reasoning.
Which power of ten?
Choose the nearest power of ten in metres for Human, 70 µm hair, 2 µm bacterium, Football pitch, Mount Everest, Earth and Sun. For example, 1.75 m is nearest to 100 m.
Put them in order
Arrange Virus, 2 µm bacterium, 70 µm hair, Human, Blue whale, Mount Everest, Earth and Sun from smallest to largest. Check the surprising close calls with virus vs bacterium and Earth vs Sun.
Count the orders
Compare the nearest exponents for DNA and hair, Earth and Sun, then Burj Khalifa and Everest. State the exponent difference and convert it into an approximate multiplier. A difference of 3 means 103 = 1,000 times.
Write standard form
Rewrite these measured lengths in scientific notation (standard form): hair 70 µm, bacterium 2 µm, football pitch 105 m, Everest 8.849 km, Earth 12,740 km and Sun 1,391,000 km.
Estimate before revealing
Predict the order of magnitude for DNA double helix, Virus, Blue whale, Saturn, Mount Everest and the Earth–Sun distance. Record why each estimate feels plausible, then open the entity pages.
Big question
Why can a difference of only 6 in the exponent describe objects that feel unimaginably different in size? Which was harder to estimate: microscopic or astronomical scales? Explain your reasoning.
For teachers
Teacher guide & notes
The downloadable guide contains answers and differentiation. This summary is enough to run the lesson from the page.
Suggested 25–35 minute flow
- 5 minutes
- Model one 10× step and distinguish an exponent difference from a multiplier.
- 15–20 minutes
- Pairs complete estimation, ordering and standard-form tasks, checking only after committing.
- 5–10 minutes
- Use the journey to discuss errors, boundary cases and the final reasoning question.
Key teaching points
- An order of magnitude is specifically a factor of ten.
- A difference of 3 exponents means approximately 1,000×, not 3×.
- Negative exponents describe positive quantities smaller than one metre.
- 10-6 is smaller than 10-3.
- An entity can occupy different orders depending on whether students compare height, width, diameter or distance.
Measurement note: examples are representative measured dimensions, not claims that every cell, virus, person or galaxy has one exact size. DNA uses helix diameter; Everest uses elevation above mean sea level; Solar System uses the diameter of Neptune’s orbit.
Activity 2 of 2
Continue the series
Return to the first activity for ratios, estimation and calibrated side-by-side comparisons.
Keep exploring
Follow the scale
Licence: This educational resource and its downloadable worksheet, teacher guide and complete pack are licensed under CC BY-NC-SA 4.0. Created by Just How Big? / Katipo Technologies Ltd. Other site data, illustrations and software retain their own terms.