Lesson 139: Mixing and separating materials

🔬 SCIENCE (40 Lessons) • 🟡 C. Materials and Matter

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Objective

I can talk about what happens when I mix simple materials together and try easy ways to separate them again. I can say when things are all together in a mixture and when they are apart.

Materials

Mini-lesson — Mixing and separating materials

In science we often mix things together and see what happens. When we mix things, we make a mixture.

What is a mixture?

  • A mixture has two or more materials together in one place.
  • For example, a bowl with rice and beans mixed, or cereal with flakes and raisins.
  • We can still see the different pieces in many mixtures.

Mixing materials

  • When we stir rice and beans in a bowl, the pieces move around and mix.
  • When we put sand in water and stir, the water looks cloudy. Sand and water are now mixed.
  • Sometimes tiny pieces seem to disappear in water (like sugar) but they are still there in the mixture.

Separating mixtures

  • We can often separate mixtures again.
  • We can pick out bigger pieces with our fingers (for example, pick out the raisins from cereal).
  • We can use a strainer or sieve to let small pieces fall through and keep bigger pieces on top.
  • We can wait for heavy pieces like sand to fall to the bottom of water.

Together and apart

  • When things are mixed, they are together.
  • When we separate them, they are more apart.
  • Mixtures help us see how materials can change place but still be the same materials.

Scientists carefully watch what happens when they mix and separate materials. You can be a young scientist too by looking closely and talking about what you see.

Picture strip: Mix it, then separate it

Before mixing

After mixing

Separating again

Guided Practice — Make and separate a simple mixture

You will make a small mixture with dry foods and then try to separate it again. Work with an adult and only use safe materials.

  1. Start with two bowls: Put rice in one bowl and beans in another (or two other small foods).
  2. Look closely: In your notebook, draw what you see in each bowl. The materials are still apart.
  3. Mix them: Pour both bowls into one larger bowl. Gently stir with your hand or a spoon. Now you have a mixture.
  4. Talk about it: Say, "This bowl is a mixture of rice and beans." Can you still see both?
  5. Separate by hand: Use your fingers to pick out just the beans into a new bowl. How long does it take?
  6. Try a tool: If you have a strainer, gently pour some of the mixture in. What stays on top and what falls through?
  7. Use the tracing pad: Choose words like mix, separate, together, apart, rice, or beans and trace them. Say the words as you write.
Tracing Pad
Tracing snapshot for print
Tip: As you trace, say a sentence like "I mix materials" or "I separate the mixture".

Practice 1 — Mixture or not?

Decide which things are mixtures and which are not.

  1. Draw two headings on your page: "Mixtures" and "Not mixtures".
  2. Under Mixtures, you might write: rice and beans, cereal and raisins, fruit salad, trail mix.
  3. Under Not mixtures, you might write: one banana, a plain glass of water, one apple.
  4. Talk with an adult: Why is fruit salad a mixture, but one banana is not? Use the words together and apart.

Practice 2 — Mixing with water

Explore what happens when you mix water with other safe materials.

Practice 3 — My mixture picture

Create your own mixture picture and explain how you would separate it.

  1. Draw a bowl or plate and fill it with a fun mixture, such as pasta and peas or cereal and fruit.
  2. Use different colours so we can see the different materials.
  3. Write one or two sentences, such as: "This is a mixture of pasta and peas. I can separate it by picking out the peas."
  4. Show your picture to someone and explain how you would separate your mixture.

Quick Check — Mixing and separating materials

Answer each question about mixtures and how we can separate materials again.

1) What is a mixture?

A mixture has two or more materials together in one place.

2) Which one is a mixture?

Cereal and raisins are different materials mixed together.

3) When we mix rice and beans in one bowl, what do we get?

Both rice and beans are still there together in a mixture.

4) Which words go with the idea of a mixture?

In a mixture, materials are together and mixed.

5) What does it mean to separate a mixture?

Separating means taking mixed materials apart again.

6) How could you separate a mixture of pasta and peas in a bowl?

You can separate bigger pieces by picking them out.

7) Which tool can help separate some mixtures of big and small pieces?

A strainer or sieve lets small pieces fall through and keeps big ones.

8) A bowl with strawberries, bananas, and apples together is best called…

Different fruits together make a fruit mixture.

9) When we mix sand and water, what do we see at first?

Sand and water together make a cloudy mixture.

10) After sand and water sit still for a while, what often happens?

Heavy sand settles at the bottom, which helps us separate it.

11) Which sentence shows a child thinking like a scientist about mixtures?

This sentence watches carefully and explains mixing and separating.

12) Which is the best way to describe fruit salad?

Fruit salad is a mixture of different fruits.

13) How might you separate a mixture of buttons and paper clips?

Using your hands to sort pieces into groups is a simple way to separate.

14) Why do we learn about mixing and separating materials?

Knowing about mixtures helps us understand and use materials around us.

15) Which sentence shows a good understanding of mixtures?

This sentence explains both mixing and sometimes separating again.

Assessment (parent/teacher)

Exit ticket (student)

Next time I will practise…

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