Explore Sun Safety With UV Beads

If your family is anything like mine, summer means it is time to get out and play in the sunshine!  Of course, playing in the sun means taking precautions against things like sunburn.  Even on a cloudy day, the sun can cause serious damage to your skin.  Most people assume that if you can’t see the sun, you don’t need to worry about protecting yourself.  Unfortunately, this isn’t the case.  In fact, the visible light that comes from the sun isn’t responsible for sunburn.  Instead, it is an invisible form of light called ultraviolet (UV) light.  In this little exploration, you will learn how to use a very special type of plastic bead to detect UV light.

Here’s What You Need 

• UV beads (you can find them at Steve Spangler Science, Arbor Scientific, or other online science supply vendors)
• Plastic or leather cord
• Sun screen (optional)
• Plastic sandwich bags (optional)
• Permanent marker (optional)

Here’s What You Do

Do the first part of the activity inside and away from any sunlight (e.g. stay away from windows).  Take the white UV beads out of the bag and expose them to light in your home.  Most of the light inside our homes is fluorescent or incandescent light…not UV.  Did your beads change in any way?

Now, take your beads outside and expose them to the sun.  Do you notice anything?  The white UV beads will change color depending on the pigment in the bead.  The color change is not permanent.  When you head back inside and away from the sunlight, the beads will become white again.  In fact, the beads will change color about 50,000 times before they stop responding to UV light!

You can use the plastic or leather cord to create a necklace or bracelet of UV beads.  Now, you will have a way to quickly detect UV light and remind you to wear your sunscreen. Jewelry the practical, fun, and educational…you have to love that!

You can also use the UV beads to test different brands of sunscreen.  If you’re like me, you probably have a few different brands hanging out under the bathroom sink. Try to find some with different Sun Protection Factors (SPF) ratings.  Now, grab your plastic sandwich bags.  You will need one bag for each of the sunscreens you want to test.  You will also need an extra bag to use as a control (something to compare to your other bags). While inside, place some UV beads in each of the bags. Rub a different sunscreen on the outside of each of the bags.  Use the permanent marker to label each bag.  Make sure you also prepare a bag of beads with no sunscreen on the bag.  Now, it is time to experiment!

Take your sunscreen-covered bags and your no-sunscreen bag outside and lay them in them on the ground in the sun. Do you notice any difference between the bags?  Are the colors darker in some bags?  Make a note of which bags have the darkest colors.  You might notice a connection between the color of the beads and SPF rating on the sunscreen.  Sunscreens with a higher SPF rating block more UV light energy.  The beads in these bags should be lighter than those in the other bags.  Of course, all the beads should be lighter than those in the unprotected bag. It just goes to show that some sunscreen is better than no sunscreen at all.

Note: You can also use this experiment to test different bands of sunscreen. However, if you want to test different brands make sure they all have the same SPF rating. 

The Science Behind the Beads

The UV beads used in this activity were created using a special pigment that responds to UV light energy.  UV light cannot be detected with our eyes.  In fact, our eyes can only detect a certain type of light energy called visible light.  Other animals, however, can see UV light.  For example: Butterflies can use ultraviolet markers to select a mate. Reindeer rely on ultraviolet light to find the lichen they like to eat.  Bees use UV light to hone in on UV markings of certain flowers like the Black-eyed Susan.  While we cannot see UV light, it is there whenever the sun is in the sky.  That includes cloudy days, rainy days, and winter days!

Just like visible light, there are different types of ultraviolet light. Short wave ultraviolet light is used to identify fluorescent rocks and kill bacteria.  You are probably more familiar with long wave ultraviolet light.  In fact, you have probably used them in your home around Halloween.  That’s right.  Long wave ultraviolet light is the type of light that is created by black lights (those cool lights that make your clothes and decorations glow)!

Many people love to play in the sunshine.  However, when your skin is exposed to sunlight for extended periods of time it changes.  The UV light energy can beak the chemical bonds in your skin causing it to wrinkle and lose flexibility.  Too much of this type of exposure can also lead to skin cancer.  Sunscreens are designed to block UV light.  They act as a barrier between the dangerous and invisible UV light and your skin.  As a result, it is important to select the right sunscreen and reapply it continuously if you are going to be spending a lot of time outside.  There you have it; some of the science behind UV light.  Have fun in the sun this summer, wear your UV bead bracelet, and use your sunscreen!

Homemade Black Snake Fireworks

I've gotten lots of request to post some science activities related to the fourth of July and more specifically...FIREWORKS! Many of you wanted to know the science behind fireworks and if it is possible to create fireworks at home.  In response to those requests...here is a great way to create some of those intriguing Black Snake fireworks that you see every year around this time.  This activity requires the use of fire and some flammable liquids, so adult supervision and safety precautions are a must (make sure you have a fire extinguisher or water nearby)!

Here's What You Need

• Sand
• A high-percentage alcohol (ethanol) - I use grain alcohol (e.g. Everclear)
• Powdered sugar (sucrose)
• Baking soda (sodium bicarbonate)
• A grill lighter or long match
• Aluminum foil or a foil pie plate

Here's What you Do

First, let's start by making our baking soda and sugar mixture.  In a bowl, mix 4 tbsp of powder sugar with 1 tbsp of baking soda.  Once you have those two ingredients mixed well, place the bowl to the side.  We will use in later. Create a mound of sand in the middle of the foil/pie plate.  Use your finger to make an indentation in the middle of the mound of sand.  This is where you will pour your alcohol and the other ingredients.

Use your finger to make a small indentation in your mound of sand.

Measure 3 tsp of alcohol and carefully pour it into the indentation.  Now, let's add the baking soda and sugar mixture.  There are a couple of ways that you can do this.  Each way will give you a different kinds of snake(s).  First, you can sprinkle 1 tsp of the baking soda and sugar mixture into the indentation in the sand mound.  Another method is to pack 1 tsp baking soda and sugar mixture into the measuring spoon.  This will create a little spoon shaped tablet that you can drop into the indentation in the sand mound.  In either case, don't pack the mixture down into the indentation.

This is what your setup should look like.  Now, we are ready to light it!

Have an adult use a long match or a grill lighter to ignite the alcohol.  The flame will initially be very hard to see (the alcohol burns blue).  However, you will know it is lit when you see the baking soda and sugar mixture begin to blacken as it burns.  You might also smell something very familiar - roasted marshmallows (that's the sugar burning)! It will take a while before the snakes really start to grow, so be patient.  After a while, you will see the baking soda and sugar mixture start to bubble.  Slowly, the black snakes will start to grow from the sand!  Make sure the flame is out before you attempt to touch or pick up the snake.  When you've done it once, grad some more baking soda and sugar and do it again.  Just make sure you mix your sand and reform you sand mound after each attempt.  You will get different types of snakes each time! 

You'll get a different kind of snake each time you do the activity

The Science Behind the Black Snakes

When baking soda (sodium bicarbonate) gets hot, it produces a gas - carbon dioxide.  This is the same gas that gives soda its fizz.  In addition to carbon dioxide, the baking soda also creates water vapor and sodium carbonate.  When the sugar (sucrose) is heated, it also creates carbon dioxide and water vapor.  All that carbon dioxide has to go somewhere.  It bubbles up and out of the mixture.  However, as it does this, it pushes the carbonate up and out of the sand. That's where the black snake(s) comes from!  The snake is basically layer upon layer of that element we know and love - carbon!