Making mixtures: physical changes and chemical reactions

Experiment freely with mixing a variety of solids and liquids, and find that each mixture has different properties. Discussion on new properties observed and/or physical/chemical change.
Science content
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Physical Changes, Solutions, Mixtures and Separating (2, 4, 5, 6)
Chemistry: Chemical Changes (2, 7)
  • paint tray or ice cube tray
  • coffee stirrer sticks
  • a variety of solids in separate cups e.g. flour, sugar, cornstarch, baking soda, optional: salt, rice, sand. For Ks, maybe only baking soda and flour
  • a variety of liquids in separate squeeze bottles e.g. water, vinegar
  • waste pot for used sticks
  • cloths for clean up

This activity has been run using the Play-Debrief-Replay model of science education described in "The New Teaching Elementary Science" book (see resource).

Students try mixing different combinations of solids and liquids and the teacher records the new textures they find.
At some point, optional with age, encourage pair-wise mixing so that students can determine which substances produce the result seen.
Students can optionally write down their discoveries as they make them, so that they can refer to them when the group is brought together to discuss findings.

Some expected outcomes and terminology with the materials listed for older students:
Absorb: some solids will soak up liquids
Dissolving: some solids will “disappear” into the liquid as they dissolve in it. Solute/solvent.
Suspension: some solids will disperse in a liquid but not dissolve, to make a suspension.
Solutions and suspensions are both kinds of mixtures.
Chemical reaction: some solids and liquids will react together to make new things (gas bubbles appear when baking soda and vinegar are mixed).

Discussion with lower primary students:
The various mixtures make different textures: goopy, sloppy, slimy. Some mixtures make bubbles or foam. The textures of the starting materials, as solids and liquids, can also be discussed.
Materials that we use every day have these properties, and the properties make them useful for us. Foams are made by soap, which is useful for cleaning. Goopy mixtures can make glues.
Liquids that flow can be poured from one container to another. Solids that keep their shape can be picked up.
Mixtures that make bubbles of gas can be used for many things, for example, to make interesting candies (pop rocks), or even can be used to send rockets to space (the gas pushes out of the back to make the rocket go up).

How do we know if there has been a chemical changes?
A chemical reaction produces a change in the molecules. Indicators of a chemical change are production of a gas or precipitate or a change in colour or smell.


This is a general exploration of mixtures and chemical reactions. For a more focused exploration of mixtures (suspensions, solutions and colloids) see Making Mixtures.

Grades taught
Gr K
Gr 1
Gr 2
Gr 3