Design an experiment to test UV

How can you protect yourself from UV radiation?

• What are some things you might use to protect yourself from UV?

SunscreenSunglassesHatClothingShade

How will you know if you have been exposed to UV?

• We can’t see UV with our eyes so we will need a sensor to monitor it

• We have plastic beads that change color with exposure to UV

Design Experiment Step 1

Select an independent variable to test: something that will block the UVMaterials we have: • 4, 15 and 45 SPF sunscreen (apply to clear

plastic)• White T-shirt material• Aluminum foil, Plastic wrap, white paper• Your own hat, sunglasses, hair, shirt, jacket etc.

Design Experiment Step 2

Identify your dependent variable:How will you know if the UV exposure changed because of your choice of independent variable to block the UV?The color change in the beads – how long it takes and how dark it becomes (put on scale of 0 no change to 5 darkest

Design Experiment Step 3

Create a control group so you know what would have happened to the bead color without your independent variable blocking the UV. Control groups give you a basis for comparison.

UV beads exposed to the sunlight without anything to cover them – how long does it take them to get dark?Test your control group first so you know what to look for with your experimental group

Constants (Controlled Variables)

Things that you keep the same between your groups to make it a fair test.What things will affect the changing color of the beads?Exposure to UV light

How can you control the exposure to UV light?

• Cover the beads until you are ready to test them (aluminum foil covered petri dishes)

• Watch out for shadows• Same angle towards the sun• Cover beads with your independent variable as

soon as you remove the cover on the petri dish• Same amount of time exposed before rating

darkness of bead

Write Up In Notebook

• Title – must include independent and dependent variable

• Independent Variable• Dependent Variable• Hypothesis• Control group• Constants/Controlled variables• Data table• Graph of numeric data (time or darkness rating)• Conclusion

Data Table

Need a column for Independent variableNeed a column for Dependent variableRow for each trial you conduct