Size ladder: atom to Earth sim
Drag a zoom slider along a powers-of-ten rail from 10⁻¹⁰ m to 10⁷ m and record the real objects that come into view, from a hydrogen atom to the Earth, with their sizes in prefixes and standard form.
Physical quantities, units and measurement · covers the O-Level, IGCSE, GCSE topic
What the sim shows
The screen shows a view a certain width across, from 10⁻¹⁰ m (about one hydrogen atom) to 10⁷ m (about the Earth). Each whole step along the rail is a power of ten: the view gets 10 times wider. The small marks between are 2, 3 … 9 times, so the scale is a log scale. Every object is drawn at its real size compared with the view, with sizes from published sources (README). The SI prefixes are exact powers of ten: n (nano) 10⁻⁹, µ (micro) 10⁻⁶, m (milli) 10⁻³, c (centi) 10⁻², d (deci) 10⁻¹, k (kilo) 10³, M (mega) 10⁶, G (giga) 10⁹, T (tera) 10¹². Sizes of living things vary, so those are typical values. The shapes are simple outlines, not pictures. Nothing this small can be seen with light: atoms and viruses are measured with electron microscopes and other methods.
- Zoom slider: each step along the rail makes the screen 10 times wider or narrower
- Viewer screen: real objects shown at their true size for that width
- Rail scale: powers of ten in metres, with the SI prefixes under it
Use it in your lessons
- Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
- Present it and share student links with the teacher plan, from US$5 a month, billed yearly.
- Put it on your own website or LMS for US$9, paid once, or every sim from US$29 a month.
Free guide: 12 practicals as sims, and how to run one in a lesson →
Need a version for your exact set-up? Have one made: US$49 a figure in an order of 5.
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