Bird Watch
Stage: 2 and 3 Challenge Level: 
Do you know which birds are regular visitors where you live?
Terrariums
Stage: 3 Challenge Level:
Build a mini eco-system, and collect and interpret data on how well the plants grow under different conditions.
Capture and Recapture
Stage: 3 and 4 Challenge Level:
How do scientists or mathematicians estimate the size of a population of wild animals?
Big and Small Numbers in the Living World
Stage: 3 and 4 Challenge Level:
Work with numbers big and small to estimate and calculate various quantities in biological contexts.
Investigating Epidemics
Stage: 3 and 4 Challenge Level:
Simple models which help us to investigate how epidemics grow and die out.
Maths Is Everywhere!
Stage: 3 and 4 Challenge Level:
Maths is everywhere in the world! Take a look at these images. What mathematics can you see?
Biology Measurement Challenge
Stage: 4 Challenge Level:
Analyse these beautiful biological images and attempt to rank them in size order.
Time to Evolve
Stage: 4 Challenge Level:
How many generations would link an evolutionist to a very distant ancestor?
Robot Camera
Stage: 4 Challenge Level:
Could nanotechnology be used to see if an artery is blocked? Or is this just science fiction?
Using the Haemocytometer
Stage: 4 Challenge Level:
Practise your skills of proportional reasoning with this interactive haemocytometer.
Like Father Like Son
Stage: 4 Short Challenge Level:
What is the chance I will have a son who looks like me?
Counting Fish
Stage: 4 Challenge Level:
I need a figure for the fish population in a lake, how does it help to catch and mark 40 fish ?
Counting Dolphins
Stage: 4 Challenge Level:
How would you go about estimating populations of dolphins?
Big and Small Numbers in Biology
Stage: 4 Challenge Level:
Work with numbers big and small to estimate and calulate various quantities in biological contexts.
Solving the Genome Puzzle
Stage: 4 and 5
The human genome is represented by a string of around 3 billion letters. To deal with such large numbers, genome sequencing relies on clever algorithms. This article investigates.
Influenza Virus: It's All in the Packaging
Stage: 4 and 5
This article explores how researchers in disease dynamics are using mathematics to understand how the influenza virus replicates.
NRICH is part of the family of activities in the Millennium Mathematics Project.