Thursday, March 11, 2010

Mixtures: The Mistake


This is a fun, open-ended lab for your students to put into practice that which they've learned about separating mixtures. Read the following story to your students (this is the original, you'll want to swap out "Home Ec" for whatever's appropriate in your school). Then, provide them with a sample of the salt and pepper mixture, a variety of tools, and let them have at it.

You may want to read the story to them the day before they'll perform the separation... gives them time to come up with a plan and gives you the opportunity to gather any materials they may wish to use that you hadn't thought to put out.


The Mistake
What kind of day was it? A day like all days - only THE SUBSTITUTE was there. The place was Home Economics and the substitute - one Mrs. Dimwitty. In her demonstration, Mrs. Dimwitty was to add salt and pepper to her baked dish. In trying to save time, Mrs. Dimwitty mixed the salt and pepper together before class. Upon reading teh recipe very closely, she discovered that the salt and pepper had to be added at different times. What an embarassment. What would she do now? All teh salt and pepper she had was in one jar - all mixed up. One of Mrs. Dimwitty's students said she could help if allowed to go to the science department. A short time later she came back with two jars - one containing salt, the other containing pepper. What a relief. The casserole would be a success.

In this lab you are to separate the salt and pepper mixture that you find in your test tube into two piles. Salt must be piled on one paper towel - pepper on another. You WILL NOT get another test tube so be careful. Don't throw anything down the drain until the end of the period. After you have separated the salt and pepper, bring them to the front desk for inspection. There should be no salt in the pepper and no pepper in the salt. After your separation has been approved, give a step by step description of what you did on the back of this sheet.

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