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Dissolving and Separating Mixtures: Molly's Mixture Lab

Dissolving and Separating Mixtures: Molly's Mixture Lab

Learn how solids dissolve to make a solution and how to separate mixtures by sieving, filtering and evaporating in Molly the mole's lab.

Chapter 4: Evaporating: recovering a dissolved substance from a solution
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What you'll learn

  • Some solids dissolve in a liquid to make a solution
  • Soluble materials dissolve; insoluble materials like sand do not
  • Why dissolving is different from melting
  • How a sieve separates solids with different-sized pieces
  • Filtering catches an insoluble solid but not a dissolved one
  • Evaporating the water leaves a dissolved solid behind as crystals

Chapter by chapter

  1. Dissolving: soluble and insoluble materials make a solution Free to try

    Year 5 science · 1

  2. Sieving: separating solids with different-sized pieces

    Year 5 science · 2

  3. Filtering: separating an insoluble solid from a liquid

    Year 5 science · 2 Year 5 science · 1

  4. Evaporating: recovering a dissolved substance from a solution

    Year 5 science · 1 Year 5 science · 2

  5. Choosing a method: separating mixtures by sieving, filtering and evaporating

    Year 5 science · 2 Year 5 science · 1

  6. Mixture Lab Challenge (10 questions) (10 questions)

See every Science chapter in the chapter library

What the chapters cover in the national curriculum in England:

  1. Year 5 science: Know that some materials will dissolve in liquid to form a solution, and describe how to recover a substance from a solution
  2. Year 5 science: Use knowledge of solids, liquids and gases to decide how mixtures might be separated, including through filtering, sieving and evaporating

About this adventure

Dissolving and Separating Mixtures is an interactive science game that teaches children aged 8–11 how some solids dissolve in a liquid to make a solution, and how to separate mixtures again by sieving, filtering and evaporating.

In Molly the mole's lab, players stir sugar into water, zoom in to see that it has broken into pieces too tiny to see, and test six solids to sort them into soluble and insoluble. They shake peas out of rice, pick a sieve with the right size holes, fold filter paper into a cone, and leave salt water on a sunny windowsill until salt crystals appear.

Along the way they compare dissolving with melting, find out why filter paper cannot catch dissolved salt, and finish by separating gravel, sand and salt in the right order. Questions use typed answers as well as choices.

Questions and answers

What is the difference between dissolving and melting?

Melting happens when a solid gets warm enough to turn into a liquid, like chocolate in a warm pan. Dissolving happens when a solid breaks into pieces too tiny to see and mixes into a liquid, like sugar stirred into tea.

How do you get salt back from salt water?

You evaporate the water. Pour the salt water into a shallow dish and leave it somewhere warm: the water turns into water vapour and goes into the air, and salt crystals are left behind. Sieving and filtering cannot do this.

When should you use sieving, filtering or evaporating?

Use a sieve for solids with different-sized pieces, such as gravel and sand. Use filtering for a solid that has not dissolved in a liquid, such as sand in water. Use evaporating to get back a solid that has dissolved, such as salt.

What age is this dissolving and separating game for?

It is made for children aged 8 to 11, especially Year 5. It follows the KS2 science national curriculum in England for dissolving, recovering a substance from a solution and separating mixtures.

What does the game include and how long does it take?

It has five lab stations, an optional warm-up on solids, liquids and gases, a quick check after each station and a 10-question final challenge. Playing everything takes about 50 minutes, and children can play one station at a time.

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