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Activity

Discover mixtures, physical changes and chemical reactions through free experimentation

Summary: 
Experiment freely with mixing a variety of solids and liquids, and find that each mixture has different properties. Discussion on kinds of mixtures and/or physical and chemical change.
Science content (2016 curriculum): 
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)
Materials: 
  • ice cube tray (not white), or little pots to mix in e.g. dollar store shot glasses
  • coffee stirrer sticks
  • a variety of solids in separate cups e.g. flour, sugar, salt, rice, sand, baking soda
  • a variety of liquids in separate squeeze bottles e.g. water, vinegar
Procedure: 

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 record what they find.
At some point, if necessary, encourage pair wise mixing so that they can determine which substances produce the result seen.
Students write down their discoveries, 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).

Notes: 

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

Kindergarteners at Tyee were given baking soda, vinegar, water and sugar. They were asked to find a chemical change (when it looks different).
baking soda, vinegar, flour, water, sugar

Grades taught: 
Gr K
Gr 1
Gr 2
Gr 3
Teacher: 
Barbara Duncan
Becky Evermon
Cindy Woo
Ingrid
Patricia Ellis
Wendy Zwaagstra
Teaching site: 
MacCorkindale Elementary
Laurier Elementary
Selkirk Elementary
Tyee Elementary
Activity originally developed and delivered: 

Scientist in Residence Program, Vancouver.