5th grade · Science · Unit 1 of 12
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).
New York State Learning 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 New York
In the New York State Learning Standards, this is unit 1 of 12 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.
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
Kenji has a dry mix of iron filings, sand and salt. Put his separation steps in order.
- ☕Pour it through a filter to catch the sand
- 🧲Run a magnet through the dry mix to pull out the iron
- ☀️Let the water evaporate to leave the salt
- 🥄Add water and stir until the salt dissolves
Run a magnet through the dry mix to pull out the iron → Add water and stir until the salt dissolves → Pour it through a filter to catch the sand → Let the water evaporate to leave the salt
Hint: Use the magnet while the mix is still dry. Then dissolve the salt, filter out the sand, and evaporate the water to get the salt back.
Question 2
Water is called the 'universal solvent.' Why?
- it can dissolve many different substances
- it never mixes with anything
- it is only found on Earth
- it can dissolve every substance
it can dissolve many different substances
Hint: Water dissolves more substances than almost any other liquid, but not everything. Oil and sand don't dissolve in it.
Question 3
A dot of black marker on wet paper spreads out into several colors. What is this separation method called?
🖊️- filtration
- sieving
- evaporation
- chromatography
chromatography
Hint: In chromatography, water carries each ink color a different distance up the paper, separating the mixture.
Question 4
When salt dissolves in water, which part is the solute?
🧂- the water
- the salt water
- the salt
the salt
Hint: The solute is what dissolves (salt). The solvent does the dissolving (water). Together they make a solution (salt water).
Question 5
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 18 g Powder B 9 g Powder C 40 g Powder D 4 g - Powder D
- Powder C
- Powder A
- Powder B
Powder D
Hint: The least soluble substance dissolved the smallest amount. Find the smallest number.
Question 6
Why can't a filter separate salt from salt water?
- salt is attracted to magnets
- the salt has turned into water
- filters only work with hot water
- the dissolved salt particles are tiny enough to pass through
the dissolved salt particles are tiny enough to pass through
Hint: Dissolved salt is spread out as tiny particles mixed among the water, so it flows right through a filter.