Balloon Blow Up Lab

I use this lab as an introduction to the basic chemistry portion of the living environment curriculum. It is a pretty elementary experiment that many children have done in one form or another (Volcanoes!) but they may not have measured the results and considered the chemical reactions taking place or used a graph to estimate the equivalence point (the mass of baking soda at which the number (moles) of both reactants would be equal and hence used up). I calculated their molar masses and figured out that with 50 mL vinegar, that point should be somewhere between 5 and 10 grams of baking soda, unless I made an error somewhere. Please let me know if you find a mistake.

I also added the bromthymol blue piece to the lab, which I haven't done before. It’s optional if you don’t have any. It is added in the initial test (1 gram) only, just because I like to introduce indicators as early as possible to use as an example later on when I get the inevitable, “how do scientists know…?” It illustrates one example of the ingenuity that goes into seeing things that can’t be seen.

I've done this lab for a long time, back to my middle school days, but in writing it up this summer I took some of the introductory text from K-12 Outreach: NSF & Science and Technology Center for Environmentally Responsible Solvents and Processes (CERSP)

Here's my version. I'm getting a little fatigued from all the summer work. I am busily working on flashcards, curriculum mapping, etc., and writing these labs is mentally draining - this may be the last one for a while.

Chemical Reactions: Balloon Blow Up

Plant Respiration

Another lab that I have not yet tried, it comes from The American Biology Teacher (Lisa Weise, The American Biology Teacher, Volume 68 No. 5, May 2006) I've written an introduction and added my usual lab formatting, keeping the basic experimental design from the original article. It looks like a very clever way to measure relative CO2 production in radish seedlings in a modified pipette.

Plant Respiration Lab

A cotton swab soaked in an NaOH solution is loaded into the bulb of several pipettes, followed by several seedlings. The tips of the pipettes are then placed (using a home-made, cardboard holder) in a petri dish containing water. As CO2 is produced by the seedlings, it reacts with the NaOH to form baking soda, essentially removing the gaseous CO2, causing a decrease in the pressure inside the pipette. Voila, water rises in the pipette proportional to the amount of CO2 produced. Remember that the initial production of CO2 simply replaces a molecule of O2 with a molecule of CO2 so the pressure differential only comes about when the CO2 is removed.

In a related story, I'm trying to get my school to invest in Vernier's new LabQuest probeware. If that happens, I may or may not use this particular set-up. In some ways it is better for bringing in the chemistry, but on the other hand chemistry is such a big mystery to 8-10th graders, it may actually distract from the lesson. I could always do both...

Mello Jello in a Test Tube

I had been doing the mello jello lab in a petri dish as called for in the original published lab, but found it rather difficult in terms of materials management and set up. I re-worked it after "can't-remember-who's" lab using similar principles but set in test tubes instead of petri dishes. Much of the introductory material is lifted directly from the original lab. I've given full credit, so hopefully they won't come after me!

Mello Jello in a Test Tube

Protein Synthesis Lab

I've put this lab together over a the last couple of years. It annoys the kids a bit -transcribing DNA into mRNA and then translating into amino acid sequences can be a little tedious. I tried to make it a little interesting with some silly word game analogies, but still.

I have also been adding some regents exam questions at the end of each lab but I haven't got around to it yet on this one. I will automatically update the link when I get to it. Keep in mind in NY state past regents exams have used both the circular codon table I use in this lab as well as the more typical square table, so kids need familiarity with the other one as well.

Protein Synthesis Lab

Diffusion Lab

I did this lab last year without lab sheets and had students record observations in their journals. I've put the lab sheets together. As usual, I may add to it next year - for example, I'd like to add a section on calculating the rate of diffusion, but I haven't had the time or energy to put it in yet. I may also play around with putting some starch into the mix and using starch indicator instead of food coloring. Still, the basic set-up will be the same.

I've seen other labs out there that use gelatin cubes placed in food coloring or other substances and incorporate surface area:volume ratios. For now I'm keeping it simple. I use a petri dish with gelatin and add food coloring to a well in the center, then measure the distance it diffuses over a 5 day period.

An added bonus, if you wait long enough, is the growth of mold on the surface, which is a whole other science lesson in itself on extra-cellular digestion and enzymes. I generally do this lab after the detergent enzymes with jello lab, so I try to get students to make the connection before I have to point it out to them. Anyway, here it is.

Diffusion Through Gelatin