M&M lab:
Each student used 25 grams of M&M's. Each student counted the M&M's by color and compared the results, as percent of total sample, to the color mix percentages published by Mars Candy. We then calculated the percent error. All M&M's were counted at one time, demonstrating counting without replacement.
We then counted by color each sample by pulling one M&M at a time and putting it back into the sample before pulling the next M&M. The sample was shaken before each count. This demonstrates counting with replacement. The results were different from the first count for some color counts but the same for others. Sampling with replacement is used for example in counting wildlife.
The students reached conclusions concerning the importance of sample size and counting method.
Water water lab:
The purpose of this lab was to determine if the students could taste the difference between bottled water and tap water. I gave each student four samples to drink and compare: two samples with tap water and two samples with bottled water (two different brands of bottled water). I asked each student to determine which samples were bottled and which were tap water. Each student also picked the best tasting water. I asked to students to think about which variables were controlled: common cup, water samples at same temperature. Uncontrolled variables included students' taste buds (accuracy, impacted by drinking soda, smoking, etc.), whether the student was hungry or thirsty.
Results: three of six students picked correctly the two bottled water samples. The other three were half correct. Four students picked as their favorite water one of the bottled samples however two of these students picked the cheaper bottled water as best tasting.
This lead to an Economics lesson: how much is it worth to drink bottled water if only half the class could clearly differentiate the taste?
My husband, Rob, is teaching Statistics using this edition of The Practice of Statistics. (We are using this edition of The Practice of Statistics for AP, too.). Incidentally, he hates to blog. I’m going to have his post updates to his physics blog for the sake of the kids who need to have a record for their portfolios. Basically, we are planning and selecting the material together.
We selected the older edition because it’s cheaper. We’ll update data sets as we go. Rob is doing the teaching; this is the only time I’ve ever seen him uncertain about instruction. Stats are more descriptive, require graphing calculators, and experimental design. So, he and I are planning the class together,
Last week, Rob and I taught the kids how to graph with a graphing calculator. Tuesday, Rob is on his own—four of the eight kids in his class seem to be proficient with the graphing calculators. Tuesday, he’s posting a set of data and quizzing the kids to see if they can graph. After the quiz, he’s giving the kids a reference sheet for TI84. (The TI 83/84 are very similar to use.).
Next, Rob is going to finish the M&M lab. He plans to have the kids calculate percent error between their individual results, the class results, and the percentage by color in milk chocolate M&Ms. Last week, the kids were getting too involved with these calculations. I had to remind them we weren’t curing cancer—just doing an exercise to learn how to create a histogram.
There are enough candies remaining, Rob is going to have the Stat class take 25g samples and record results (30 trials) of removing candies with and without replacement, to determine which approach is best to determine the color composition of M&Ms.
I think this will take an hour. If not, Rob is going to do the ‘Water, Water’ exercise in Chapter 1 of the Stat textbook, to teach the kids about hypotheses and experimental design.
We are also leaning hard on Mrs. Daniel’s AP Statistics Class blog for ideas. Stay tuned.
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