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).
Minnesota K-12 Academic Standards benchmark: 5P.1.2.1.1 · testing whether mixing substances makes a new substance
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 Minnesota
In the Minnesota K-12 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.
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.
- 🥄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
- 🧲Run a magnet through the dry mix to pull out the iron
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
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 3
What pattern does this table show?
Sugar that dissolves in 100 mL of water (about) Water temperature Sugar dissolved 20 °C 200 g 40 °C 240 g 60 °C 290 g 80 °C 360 g - the warmer the water, the less sugar dissolves
- the warmer the water, the more sugar dissolves
- sugar dissolves only in cold water
- temperature doesn't change how much dissolves
the warmer the water, the more sugar dissolves
Hint: Read down both columns. As the temperature goes up, the grams of sugar go up too, so solubility increases.
Question 4
What does solubility mean?
- how heavy a substance is
- how well a substance floats
- how fast a substance melts
- how much of a substance can dissolve in a solvent
how much of a substance can dissolve in a solvent
Hint: Solubility is the amount of solute that can dissolve in a certain amount of solvent at a certain temperature.
Question 5
Which tool would best separate sand from water?
- a magnet
- a filter, like a coffee filter
- a thermometer
- a ruler
a filter, like a coffee filter
Hint: A filter lets water through but catches the bigger, undissolved sand grains.
Question 6
A sieve separates the parts of a mixture by their…
- magnetism
- size
- color
- temperature
size
Hint: Small pieces fall through the holes in a sieve; bigger pieces stay on top.