Toothpick / matchstick lab idea

Since I am going to use the "Measure the value of pi" lab for introducing graphing, equation editors and potentially writing a lab report, I want to have a lab where the goals and the experimental procedure is developed by the students in the class from top to bottom as much as possible.  Here's my idea:

I plan to give students a taped box of matches or toothpicks with a random number of matchsticks or toothpicks in them. Alternatively, I could have a single full box that students could have with the ability to put as many or as few matchsticks or toothpicks in as they choose.  Hmmm….going to have to think about that one.

There will be only one rule: students cannot open any box until the lab is done and the report is written.

I'm going to ask students: What do you want to know about the box?  I want them to write their questions down before they say anything. Then I'll have them discuss in small groups with whiteboards.  Then we'll have a short all-class discussion of the questions they are interested in.

I am hoping that the groups will come up with at least "How many matchsticks (or toothpicks) are in my box?" But I would also be thrilled if they came up with questions like "What is the mass of a single matchstick (or toothpick)?" and "What is the mass of the box (and tape)?"  These are my goals for the lab, it will be interesting to see what the class comes up with. If needed, we can have a discussion which leads us to these goals.

I will have prepared ahead of time several identical boxes each with a unique number of matchsticks or toothpicks in them and marked on the box itself. I will try to use the same amount of tape on each box, so each box is as identical as possible.

This is the first lab where I will encourage the students determine the process by which they will meet the goals of the lab. I don't know if it's the best way to encourage this process, but it should be a good follow up to the pi lab.  I don't think there are many ways to find the mass of a single matchstick or toothpick, the mass of the box and the unknown number in the initial box, other than using a linear fit model, but I'll leave the students to figure that out.

I want to have students make predictions or guesses for the quantities they want to measure before doing the lab. I think it will be interesting to see how these guesses compare to the experimental data. We can have some discussions about orders of magnitude if there are wildly varying guesses.

Then we'll do the lab. I tried this myself and it went really quickly.  There's not much to do other than mass the boxes and record the data.

I want to make sure every student has a graph of the data and has used equation editor to express their best fit line equation.  If time permits, I want to have them start to write the lab report.

My worry with this lab is again that it is too easy.  I hope that by emphasizing the students' control of the goals and procedure it will hold their attention to the end of the lab.  Plus, if we finish early, I have an idea for the next lab to do.  :-)