Summary 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) Science competencies (+ questioning + manipulation + others that are in every activity) Questioning/predicting: predicting (1 up), hypothesizing (7) Planning/conducting: planning investigations (3 up) Processing/analyzing: comparing observations with predictions (1 up) Processing/analyzing: considering alternative explanations (5 up) Evaluating: inferring (3 up) Lessons activity is in Mixtures showing physical and/or chemical changes Combining solids and liquids: mixing and floating Resource Science as Active Inquiry The New Teaching Elementary Science Materials 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 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 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 (though with young students papers end up messy, and might take away the time to experimentally play). Some expected outcomes and terminology 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 etc. Some mixtures make bubbles or foam (depending on starting materials). Materials that we use every day have their own useful properties. Goopy mixtures can make glues. Some mixtures harden like concrete. 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. Clue that a chemical change has happened: a new gas or other new state of matter, or a new colour or smell. But often, more must be known about the molecules to tell for sure. Attached documents mixing_solids_and_liquids_worksheet.pdf matter_worksheet.pdf 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. Grades taught Gr K Gr 1 Gr 2 Gr 3
