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BBiologyMathematicsS4 to S6Medicine
Medicine lab: half-life and doses (a model)
Why do some medicines have to be taken every 8 hours? Model a fictional medicine in the blood and discover half-life and exponential decay. (A model for learning only.)
LevelS4 to S6 (and A Level)
TimeAbout 35 min
You useExponentials, logarithms, half-life
PriceFree: no account
🎯 Aim
To use exponential decay and half-life to model the concentration of a medicine in the blood with repeated doses.
You will learn to
- Find a half-life from data.
- Use C = C₀ e^(−kt) with k = ln 2 ÷ half-life.
- Explain why doses are repeated at regular times.
- Explain the effect of a missed dose.
🧭 What to do
- Read the graph with a half-life of 6 h and a dose every 8 h.
- Change the Time between doses: does the level stay between the lines?
- Change the Half-life of the medicine.
- Choose Forget the 4th dose? Yes, and watch the level.
- Answer the questions with the class data.
- Write your conclusion and download your lab report.
📋 The data
Concentration of a fictional medicine after one dose.
🧠 Investigate: answer from the data
Type your answer and tap Check. Use 💡 Hint first; open the method only when you are stuck.
➕ Get more from this experiment
📝 Free
Print the worksheet (button above), download the data, and save your report. Teachers can project this page in class.
📦 Premium Lab Pack
1 000 RWF
- Worksheet: half-life with a dice or coin model
- Exponential decay and logarithm problems
- Teacher guide and answer key
- Exam-style questions with marking scheme
👩🏫 For teachers
Use it as a practical when apparatus is missing, as homework, or as a project. Free lesson plans help you plan, teach and assess.
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