5th grade · Science · Unit 1 of 9
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).
Alaska content standards learning standard: 5-PS1-3; 5-PS1-4 · identifying materials by their properties and testing whether mixing makes new substances
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 Alaska
In the Alaska content standards, this is unit 1 of 9 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: Alaska Department of Education and Early Development
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.
- ❄️The vapor touches a cold surface and condenses
- ♨️Water evaporates and the salt stays behind
- 🔥Heat the salt water
- 💧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
Is dissolving sugar in water a change that can be reversed?
- only if you freeze it
- no, the sugar is destroyed
- yes, if the water evaporates the sugar is left
- no, it becomes a brand-new substance
yes, if the water evaporates the sugar is left
Hint: Dissolving is a physical change. The sugar is still there, and evaporating the water brings it back.
Question 3
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 9 g Powder B 47 g Powder C 12 g Powder D 40 g - Powder B
- Powder C
- Powder D
- Powder A
Powder A
Hint: The least soluble substance dissolved the smallest amount. Find the smallest number.
Question 4
Which would make sugar dissolve faster in water?
🥄- using bigger sugar cubes
- using colder water
- keeping the water perfectly still
- stirring
stirring
Hint: Stirring, warmer water and smaller pieces all help a solid dissolve faster.
Question 5
Oil and water are shaken in a jar and left to sit. What happens?
- they turn into a solid
- the oil dissolves completely
- they separate into layers, with oil on top
- the water floats on top of the oil
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 6
Solution or mechanical mixture? Tap an item, then tap its basket.
Sort into: 🧪 solution · 🥗 mechanical mixture
- 🥗garden salad
- 🧃clear apple juice
- 🥜trail mix
- 🍵sugar dissolved in tea
- 🌬️air
- 🏖️sand and water
🧪 solution: clear apple juice, sugar dissolved in tea, air · 🥗 mechanical mixture: garden salad, trail mix, sand and water
Hint: A solution looks the same all the way through. In a mechanical mixture, you can see the different parts.