Award-winning video and lesson investigations on the topic of cleaning dirty water. Key concepts include:
- Cleaning dirty water can be investigated with simple equipment.
- Some materials clean muddy water better than others.
- Fine materials let the water pass through more slowly than coarse materials.
- Various materials can be used to filter out particles present in water.
- Some of these filtering materials include rocks, charcoal, sand, cotton-wool and cloth.
- The closer together the filtering material is packed, the finer the particles that can be filtered out of it.
- Looser materials remove large impurities; finer materials remove tiny impurities. The slower the ‘filtration’ speed, the cleaner the water becomes.
- Sand does not make the water absolutely clean.