Introduction
Here is a fun way to give students a chance to design and carry out an experiment. The project uses UV sensitive beads, which I ordered
from Educational
Innovations (see Hot Link below). The beads
change from white to colored when exposed
to the Sun's ultraviolet rays. They come in
packages of 240 for $6.95. I spend a couple days every fall teaching my students about the "hole in the ozone layer" before we get into the global warming issue. This activity fits nicely in this unit. The day before the first "hole in the ozone" presentation", I have students do three simple experiments to help them become familiar with the beads and get a taste of what it's like to design and experiment. Then after they have learned about "the hole", I give take part of a period to explain the project, and let them begin planning. A couple days later, they do their experiments (need good weather) and work on the poster. NOTE: I am working on a PowerPoint presentation, which will be posted on this website by Thanksgiving 2013.
Project
I explained that they would need to design, and carry out an
experiment to find the answer to one of the
questions listed below (or one of their own questions at my discretion). I let them work in groups of 2-3.
1. Does food coloring make it more difficult for UV rays to penetrate water?
2. Is old sunscreen as effective as new
sunscreen?
3. Do T-shirts block some or all UV
rays? (Do different types of clothing material block UV better than others?)
4. Does windshield glass block some or all
UV rays?
5. Are all of the windows in a car equal when it
comes to blocking UV rays?
6. Does SPF 30 sunscreen give twice the
protection of SPF 15?
7. Do UV filtering sunglasses really block UV
rays?
8. Is exposure to UV rays at midday as great
as exposure to UV rays at other times during
the day?
9. Do various surfaces (grass, concrete, pavement, dirt) reflect UV rays equally?
10. Do different colors reflect UV rays equally?
11. Does exposure to UV rays change as elevation changes?
12. Does a baseball-style cap protect your eyes from UV rays?
13. Does exposure to UV rays change as the distance from the object providing the shade changes?
14. Does a baseball-style cap protect your eyes as much as UV sunglasses do?
15. Does regular body lotion block UV rays as effectively as sunscreen?
16. Does SPF 50 lip balm block UV rays better than lip balm with no UV value?
17. Is sunscreen that was applied within the last several minutes more effective than sunscreen applied earlier in the day?
18. Does SPF 30 sunscreen work as well as SPF 50 sunscreen?
19. Do UV rays pass through a tinted plastic cup as easily as they pass through a non-tinted one.
19. Does window glass block some or all UV rays?
20. There are many more possibilities. If you come up with an idea, get it approved by your teacher before proceeding.
Scoring
A. Question: 1 point
B. Hypothesis: 2 points
C. Description of
experiment: 5 points (put this on back of poster) Others
should be able to repeat the experiment,
using your instructions. The experiment must be well-designed and clearly described to earn all 5 points.
D. Data Table: 3 points
E. Graph: 3 points
F. Observations: 2 points
G. Conclusion: 3 points
H. Comments (3 points): At least one good paragraph that may include problems you encountered, things you would do differently next time, possible further investigations, etc. - Put this on back of your poster.
I. General appearance of poster (must include A-H and a diagram) 3 points; NOTE: I provide 12" x 14" pieces of construction paper for posters.
Comments/Suggestions
1. The beads are REALLY sensitive, so keep them covered when you go outside - or be ready once you step outside. Choose 15 or 30 seconds for an exposure time and then take the beads back inside to observe the color change.
2. Design your data table and color intensity scale BEFORE you start the experiment.
3. Take precautions to eliminate background light. For example, if you are testing glasses, cover the back of the beads so that they are not exposed to UV rays reflected from the sky or surfaces.
4. Do at least 3-5 good trials. Put your exposed beads back and then get fresh ones for each new trial.
5. Use only one color of bead for all parts of your experiment. Use three beads for the control and three for each of the other parts of your experiment.
6. Baggies work well for experiments that involve applying sunscreen. Apply the sunscreen to the baggie and then put the beads inside. Loops of blue masking tape (sticky side out) can be used to secure beads in the baggies.
7. Teachers: Have plenty of snack baggies and blue masking tape ready. Consider providing food trays for students to put their experiments on as they transport experiments outside. A second tray can be used as a cover in some cases.
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