Lesson plan

Mixtures showing physical and/or chemical changes

Freely mix solids and liquids to discover different mixtures and physical/chemical changes. Follow with another physical change (e.g. glue, ooblek) or chemical reaction (e.g. soda drink, rocket) activity.
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)

Review the states of matter.
Tell students that they will mix together different liquids and solids to make mixtures.
Run mixtures of solids and liquids with free experimentation.
Run as a play-debrief-replay activity, as cited in the resource.
They will make many different mixtures. Allow students time to play, during which students will tend to mix everything all together. After a while, encourage them to simplify their ingredients to find out which minimal ingredients make one type of mixture.

For the debrief, write up all that they discover, and try to tease out the different kinds of mixtures and what minimal ingredients produced the different textures, colours and chemical changes.
Optionally discuss possible activities that students might follow up with, to explore some of these changes in more detail. Guide them through the scientific process of using controls and changing one variable at a time, before returning students to their experimenting.

Talk about mixtures around us:
Our world is made of things that have been mixed together to make new useful textures and shapes. e.g. concrete is made from sand, gravel and cement (a powder of rocks including chalk, clay and iron ore). When they are combined and dried they make hard concrete that we can build with. e.g. steel playground structures are made from iron (extracted from rocks) mixed with other chemicals.

Focus on one kind of mixture for a follow up activity:

A. Focus on baking soda and vinegar chemical reaction that makes bubbles:
Tell students they will use the same solid, baking soda, to make a soda drink or rocket. (Skip the molecule modelling for younger primaries.)

B. Focus on flour/cornstarch and water that makes variously goopy mixtures:
During debrief, discuss the different kinds of goop that students made with these ingredients. Find out how much they added. For replay, ask students to keep track of the different amounts of flour/cornstarch and water they are adding, to see what amounts make the best goop.
They can test their goops to find out which ones make the best glue..
Give students a recipe for a larger batch of ooblek.

Optional: end lesson with elephant's toothpaste, a dramatic demonstration of a chemical reaction (oxygen bleach making oxygen gas) held in a foam mixture by the dish soap.

Article with good graphic on the difference between physical and chemical changes: https://www.thoughtco.com/physical-and-chemical-changes-examples-608338

Grades taught
Gr K
Gr 1
Gr 2
Gr 3