Almost Done!

As I've mentioned before in an earlier post, my mom and I have been working on the Icky Sticky Fingers mini-unit for healthy habits. It's almost done and contains worksheets for several primary grade levels, including both bread and petri dishes experiments, as well as a poem and a craftivity for students to do. I'll have it up on my Teachers Pay Teachers soon, keep checking back for updates!

Icky Sticky Fingers #3 UPDATE

I am seriously excited about this experiment. I love the fact that we used a nutrient agar and petri dishes (it's so sciencey and introduces young kids to the science equipment that scientists use all of the time). I'm also loving this experiment because of the awesome results that I am getting. Check out the collage below!

The top pictures show the clean hand petri dishes, while the bottom pictures show the dirty hand petri dishes. All petri dishes, except for the control, have bacterial growth on them, but the dirty hand petri dishes have much more. I could look at those petri dishes forever; they are absolutely fascinating. The dirty ones have formed this film on the top that resembles plastic wrap. All of the agar is now liquified (except for the control) due to bacterial growth (and what's even better, there is no smell). This is such a great turn out, especially after the trouble I experienced in the beginning (all I had to do was move them inside to a slightly cooler spot, yet warm enough for bacterial growth). Total amount of time needed for this type of bacterial growth: 3 DAYS!!! Fast, cheap, and great results...three elements of a successful classroom experiment. 

Icky Sticky Fingers #4

Alright, here we go again, for a fourth time. This time I am going to run the same exact experiment with plain ol' cheap white bread. I also made sure that Charlie went and got his hands good and dirty in our planters. We'll see how long this one takes. Updates coming soon!

Icky Sticky Fingers #3 UPDATE

Icky Sticky Fingers #3: I ran into a couple of problems with this version, however I think I can adjust a few things to make it work. The issues I ran into are summarized below:
While the nutrient agar firmed up beautifully in the refrigerator, it melted when I put it out in the garage. I think the agar could use a little more gelatin so that it remains firm at warmer temperatures.

• Since bacteria grow well at body temperature (~98 degrees), I thought putting it in the garage would be the best place in the house (~100 degrees). It was way too warm in there and the gelatin melted. I decided to put it in the laundry room (much cooler, but the warmest place in our house...about 80 degrees). Most of the petri dishes firmed back up nicely.

Results: So far, I am noticing some really nice bacterial growth on all of the dishes, except for the control (yay!). If you look carefully at the top two photos, you'll notice the the dirty hands petri dishes have the most bacterial growth (you can't see the paper towel pattern through the media). While both clean hand petri dishes have bacterial growth, it is much less than the dirty hand petri dishes. The control petri dish was not touched at all and has no growth at all. WooHoo! Success! And such a cheap and easy experiment!

Icky Sticky Fingers Part 3!

Why not start another version of this experiment??? This time, I'm going to run the Icky Sticky Fingers experiment using petri dishes and homemade nutrient agar. I was excited to run across this very simple, very cheap recipe for nutrient agar on the internet as it could prove useful in my life science classes this year. All you need is some unflavored gelatin, a little bit of sugar, and some beef broth. You can find the recipe for nutrient agar HERE. They turned out beautifully, we'll see how they hold up over time.

Disposable petri dishes: $5.00/20 (these can be reused, sterilized in a solution of bleach water).

Gelatin: $2.50 for 4 packets.

Broth: I used prepared broth as opposed to bouillon cubes. The cost was about $1.00 per can. Each can of broth will make about 12 petri dishes.

Icky Sticky Fingers #1 and #2 UPDATES!

It's update time!

Icky Sticky Fingers Part 1: It's been 15 days and there is still no mold growth. This bread has some serious shelf life! I'm really glad we decided to try out a different type of bread with slightly different incubation temperatures due to the location (it's a lot warmer here than it was in Tahoe). I wonder how long it will take for this bread to show a little mold growth? Only time will tell...

Icky Sticky Fingers Part 2: It's only been 3 days and I'm seeing some significant mold growth! I'm getting some mixed results using the preservative free whole wheat bread. Paige's results are turning out great with the dirty bread showing more mold growth than the clean bread (see picture #1, upper left hand, top row). Charlie's dirty slice of bread has less mold growth than his clean slice of bread (see pictures #2, center (front of bread) and upper right hand (back of bread), top row). The control has the most mold growth (maybe I touched it too much when taking it out of the bag???). I'll give it a few more days and see what the final results end up being.

Icky Sticky Fingers Update

One of the most frustrating things about science is experiments that don't turn out as expected. It's been 11 days since my mom and I began our Icky Sticky Fingers experiment and I still do not see any type of mold growing on the bread (grrrr!). For a lot of students (and teachers, for that matter), this can be quite an obstacle to overcome ("My experiment failed, what do I do now?" "What do I tell my classmates/students?" "How do I explain the outcomes?" "Should I even spend more time on this?"). 

I have had many experiments turn out differently than I expected in my own classroom. What I have learned over time is that this situation is made a little easier when students come up with an explanation on their own. I have them brainstorm in small groups reasons for the outcomes that were observed. Together as a class, we decide which direction we want to go (this is modeled really good in the TV series, Mythbusters). This works well in the secondary classroom, but can be modified for the elementary classrooms with a little more teacher direction. It's hard though, with time constraints we are constantly dealing with, pacing guides, limited to no classroom budgets, and exhaustion, it is easy to say, "Forget it, let's just move on to the next unit."But you know what? We learn just as much from an experiment turns out differently than we predicted than from the ones that turn out exactly as we thought they would. 

My mom and I brainstormed some of the possible reasons why this didn't work in the time we expected it to. Some of the reasons include:

• The temperatures in Tahoe were fairly cool at night and pleasant during the day resulting in slower mold growth.
• The bread contained more preservatives that we expected (which would account for a longer shelf life).

While we will continue original experiment until we see mold growth on the bread (I'm curious how long it will actually take), today we started another experiment using a preservative free whole wheat bread from Trader Joes. From experience, this bread spoils pretty quickly (which is why I keep it in the refrigerator), so perhaps we'll get better results. Other than the type of bread and the location, the experiment was run exactly the same way as the first one. 

Additional updates coming soon!