5th grade · Science · Unit 1 of 10
Solutions & Mixtures
Dissolving and separating mixtures
What your child practices
Solutions versus mechanical mixtures, solutes and solvents, what affects dissolving, and ways to separate mixtures (filtering, evaporation, magnets, chromatography).
Arizona Academic Standards learning standard: 5.P1U1.2 · substances that combine to form new substances with different properties
How we explain it
Children can open this short lesson before they practice.
- In a solution, one substance dissolves into another, like salt in water.
- A filter separates things that don't dissolve, like sand from water.
- Dissolved salt is too tiny for a filter, so heat the water to evaporate it. The salt stays behind.
- Cool the vapor and it condenses back into pure water.
Example: How could you get the salt back out of salt water? Salt is dissolved, so a filter won't catch it. Heat the water until it evaporates. The salt is left behind. Answer: evaporate the water
Solutions & Mixtures in Arizona
In the Arizona Academic Standards, this is unit 1 of 10 in 5th grade Science, before Solid, Liquid, Gas.
Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.
Source: Arizona Department of Education
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
How can you get pure water back from salt water? Put the steps in order.
- 🔥Heat the salt water
- ♨️Water evaporates and the salt stays behind
- ❄️The vapor touches a cold surface and condenses
- 💧Drops of pure water drip into a clean cup
Heat the salt water → Water evaporates and the salt stays behind → The vapor touches a cold surface and condenses → Drops of pure water drip into a clean cup
Hint: Heat makes the water evaporate and leave the salt behind. Then the water vapor cools, condenses and drips into a clean container.
Question 2
A class tested four powders. Which powder is the least soluble in water?
Grams that dissolved in 100 mL of water at room temperature Substance Amount dissolved Powder A 25 g Powder B 18 g Powder C 12 g Powder D 4 g - Powder D
- Powder A
- Powder B
- Powder C
Powder D
Hint: The least soluble substance dissolved the smallest amount. Find the smallest number.
Question 3
Oil and water are shaken in a jar and left to sit. What happens?
- the oil dissolves completely
- they turn into a solid
- the water floats on top of the oil
- they separate into layers, with oil on top
they separate into layers, with oil on top
Hint: Oil is insoluble in water and less dense, so it rises and floats as a layer on top.
Question 4
Brass is made by melting copper and zinc together. It looks the same all the way through. What is it?
- a solid solution (an alloy)
- a pure element
- a liquid solution
- a mechanical mixture
a solid solution (an alloy)
Hint: Solutions aren't only liquids. Metals blended evenly together, called alloys, are solid solutions.
Question 5
Which tool would separate iron filings from sand?
🧲- a filter
- a measuring cup
- a magnet
- a thermometer
a magnet
Hint: Iron is attracted to magnets. Sand is not.
Question 6
A fizzy drink goes flat faster when it is warm. What does this tell you?
🥤- gases dissolve better in warm liquids
- warm drinks hold more fizz
- sugar escapes as a gas
- gases dissolve better in cold liquids
gases dissolve better in cold liquids
Hint: Unlike most solids, gases are less soluble in warm liquids, so the bubbles escape faster.