This was a busy and action-packed day for the students! After we reviewed expectations and procedures, we had to finish up with the parachute activity from yesterday. This time, the students actually tested them out in different ways (tossing them in the air, holding it upright in their hand before snatching the hand away, etc.). The students then did a brief reflection on how well it worked and more importantly: what changes could they make to improve the performance?
The students wrote a reflection piece in their notebooks about what worked, what didn't, how would they make changes, etc.
Then, we reviewed the scientific method. Each student received a copy of the following for their science notebooks:
So then we did the first experiment by exploring this question: will shining a light on a piece of paper increase its temperature? Two things about science need to be dealt with. In order for the experiment to work the conditions (control/experimental) need to be as equal as possible. In this case, I used two equal sized sheets of paper that had the exact same yellow color in order for the results to be reliable. The second thing is that there needs to be a consistent unit of measurement in order to analyze and communicate the findings.
I decided to use the familiar Fahrenheit unit of measuring temperature rather than Celsius though I will be using that too later in the year.
So I had two sheets of the exact same yellow paper each held in place to the board by a single magnet. They were separated in order to avoid the light affecting the control paper.
Students wrote down the question in their science notebooks and then made their hypothesis about whether or not shining a light on a piece of paper would increase its temperature.
Now for the experiment: I used a high power halogen bulb spotlight as the light source. I could have used a regular flashlight but this one is more dramatic both in presentation and results. I used an infrared non-contact thermometer to take temperature readings of both papers and had the students record the numbers.
I shined the light for 2-4 minutes depending on the class period and then after turning off the spotlight, I again used the infrared thermometer to take the temperatures. As most students predicted, there was a difference! The control paper's temperature remained either the same or had a slight increase. The experimental paper had a definite increase in the temperature.
I then discussed with the class how this is a preview of what will be covered later on in the year with light. Light can be reflected, refracted, or absorbed. Since the paper is opaque and no light can pass through, it absorbs the light. The light energy continues to collect on the paper and with nowhere to go the temperature increases.
The second experiment was the favorite by far! The question: is there a difference in temperature between the surface of a candy bar and its center? I used Three Musketeers bars for this experiment since they were light and fluffy enough to allow the easy insertion of a thermocouple probe.
Students again wrote the question in their notebooks and formulated their hypotheses. The only change was that they could choose between yes, no, and trace.
Each student was then given an individual-sized candy bar and a tissue to place the unwrapped candy bar on for sanitation purposes. When instructed, the students unwrapped their candy bars and placed them on the tissue. I went around and used the infrared thermometer to get the temperature of the surface of each candy bar. Each student recorded the surface temperature as I came around. Then, I inserted the thermocouple probe in each candy bar and the student recorded the interior temperature. We then compared. Interestingly enough, the interior was slightly cooler due to the fluctuations in room temperature. I did explain to the class that heat always transfers from warmer to colder (6th grade science preview) and not the other way around. If the candy bar was placed in a refrigerator for a long enough time period then both temperatures would be roughly equal.