Half-life: Watch It Decay
Watch 100 unstable nuclei decay at random, plot the graph and read off the half-life, then try the calculations.
About this activity
Half-life is hard to picture, so this shows it happening. Students let time pass for 100 unstable nuclei, see which decay at random and watch the graph take shape, then read the half-life from their own graph. They go on to read a half-life from a count-rate graph and work out activity after several half-lives. The first screen says where half-life comes in the student’s exam board (AQA, Edexcel or OCR).
How to use Half-life: Watch It Decay
- Half-life: Watch It Decay is a free Physics activity for Years 9 to 11 that takes about 10 minutes. Try it on this page on a computer, tablet or phone: there’s nothing to download.
- In a lesson, choose Show on the board to play it together as a class.
- To set it for a class, a teacher shares it and gets a code: students type the 6-digit code at lycolearn.co.uk/join with their first name and the first letter of their surname (no accounts needed), and their scores come back to the teacher.
Students will
- Explain that radioactive decay is random
- Read a half-life from a graph
- Calculate activity or count rate after a number of half-lives
- Say what half-life means
Teaching tips
- Run it twice on the board: the numbers differ each time but the half-life comes out about the same.
- Link it to the dice or coin model if you do one in class.