Pupil worksheet
What can ocean colour tell a satellite?
Read, think and draw. Use paper or a document provided by your teacher. You do not need an account or to send personal details to KEO.
Read and wonder
A satellite gathers information from far above Earth: remote sensing. Some sensors measure light reflected from the ocean. This helps scientists estimate how much chlorophyll is near the surface.
Chlorophyll is a pigment used by phytoplankton to capture sunlight. These tiny drifting organisms are important in ocean food webs. A colour measurement provides evidence, but not the whole story. Water samples and other measurements help scientists interpret it. More chlorophyll does not automatically mean a healthier ocean.
Three things to know
- Remote sensing gathers information from a distance.
- Ocean colour helps estimate surface chlorophyll.
- Scientists use context and other evidence to interpret results.
- Ocean reflects sunlight
- Sensor measures the light
- Scientists estimate chlorophyll and check other evidence
Words to explore
- Remote sensing
- Gathering information about something from a distance.
- Chlorophyll
- A pigment that helps capture light for photosynthesis.
Think it through
1. What is remote sensing?
2. Which pigment can ocean-colour measurements help estimate?
3. Does more chlorophyll always mean a healthier ocean?
Try it
Invent a colour key for low, medium and high chlorophyll. Draw a fictional map. Write one observation and one question requiring more evidence. Label it as invented data.
Sources and credits
Lesson summary and activity prepared for Kids.Earth.Org. Factual sources checked 5 November 2026.