Separating Mixtures
Use knowledge of solids, liquids, and gases to decide how mixtures might be separated through filtering, sieving, and evaporating
What a learner can do afterwards
- Choose the correct separation method for a given mixture (sieving for large particles, filtering for small, evaporating for dissolved)
- Describe a multi-step separation plan for a complex mixture like sand, salt, and water
- Explain why each method works based on the properties of the materials
The lesson
A mixture is two or more materials mixed together, not joined into something new. To separate one, look closely at what's inside. Big solid pieces need a different method than a dissolved solid you can't even see. Three tools help: a sieve, a filter, and evaporation.
Mia has a mixture of sand, salt, and water. First she pours it through a sieve to catch the biggest sand grains. Next she pours what's left through a filter paper, which traps the finer sand and lets salty water drip through. Last, she heats the salty water until the water turns to gas and floats away, leaving salt crystals in the pan.
Ask yourself: can I see and touch the solid pieces? Then sieve or filter. Has the solid disappeared into the liquid? Then evaporate. Matching the method to the material's size and whether it dissolved is the key.
Sieve for big solid pieces, filter for small solid pieces in a liquid, evaporate for a dissolved solid.
Watch it
Where it sits
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.