2nd Grade Science, Unit 1 “Measurement of Properties” – Single Substance or Mixture
P.PM.02.41 - Recognize that some objects are composed of single substances (water, sugar, salt) and others are composed of more than one substance (salt and pepper, mixed dry beans).
Substance – Anything that contains only one kind of material (salt, iron, water). Mixture - Combination of two or more types of matter which each keep their own properties. Magnetite – iron oxide that is naturally magnetic
Evaporate – changing from a liquid to a gas
Solution –When one substance dissolves in another
Dry beach sand
Dry beans (at least 3 very distinguishable types)
How do single substances combine to become a mixture?
Can a mixture be separated back into single substances?
What is a solution?
Are all solutions mixtures? (NO)
Are all mixtures solutions? (YES)
Procedures/Activities (30 minutes)
1. Begin by placing three separate piles of beans on each student’s desk. Discuss the concept of a single substance. How is each pile of bean a single substance? 2. Mix the three piles of beans into one single pile. What have we created now? Can the single substances still be separated out? Introduce the definition and concept of a mixture. 3. What if the beans were ground up and then mixed together with water? Is this a mixture (yes)? Can it be separated back into the original single substances? (no) You have no created a solution. Intro concept and definition of solution. 4. As a class demonstration, place 5 tbsp. of salt and 1 cup of water in front of the students. Explain how these are each a single substance. Mix the two together. Now we have a mixture that is a solution. Can these be separated back into their original substances? Place the cup by the window and observe for a period of days to observe as evaporation occurs and as the water is...
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