Spring Science for the End of April

We surely do love our planet.  In the spring, the sun comes out, the blossoms bloom, and animals emerge from their winter homes.  That means we can do so much observational science!  Here are a few easy activities you can try at home that will teach you about light, animals, and plants.

How Many Colors in a Rainbow
Materials
A shallow glass baking pan
Water
White paper
Red paper
Blue paper
An outdoor table or chair

Process
1. Fill your pan about half full with water.
2. Take it outside and place it on the table so that one end is sticking out over the table edge.  Make sure it doesn't fall off the table!  You can use something or someone to anchor the pan onto the table.
3. Place your white paper on the ground where the sun is shining through your pan.
4. Slowly angle your paper until a small rainbow forms.  Experiment with the angle until you can get the largest possible rainbow.  What colors do you see?  What order are they in?
5. While holding your paper so that you can see the rainbow, gently place your blue paper on top of the white paper.  What happens to the colors?
6. Remove the blue paper and replace it with the red paper.  What happens now?
7. Switch back and forth between the white, blue, and red papers and observe how the rainbow changes.

What am I observing?
You created a mini rainbow.  Rainbows are caused by reflection and refraction of light.

Refraction refers to how light bends when it passes through different materials.  When the sunlight shines through the water, like the water in your glass pan, the light bends.  White light, like sunlight, is made up of all of the visible colors of light.  All of the colors bend during refraction, but because of their different wavelengths, they bend at slightly different angles.  When the light reaches your paper, you see all the different colors reflected.

With the white paper, you probably saw all of the colors clearly because white paper reflects white light.  When you used the blue paper, some of the colors likely appeared a little crisper.  Generally, the blue dye on the paper absorbs red light, allowing green and blue light to be reflected.  Since many visible colors are made up of green and blue light, the rainbow you saw on the blue paper likely looked similar to the rainbow you saw on the white paper.

The red paper likely changed the rainbow's appearance significantly.  The red dye absorbs blue and green light, and only reflects red light.  Removing blue and green likely left a mostly orange and red rainbow on the paper.

Model Moving Pollen
Materials
3 colors of chalk powder
3 cotton balls
3 small cups
Cotton swabs
Water

Process
1. Place each powder into a different cup, along with one cotton ball per cup.
2. Dip a cotton swab in water.
3. Roll the cotton swab along each cotton ball.

What is happening?
Pollen is a light, sticky powder that flowers need to make seeds.  In this activity, the chalk powder represents pollen, the cotton swab represents hair on animals, and the cotton balls represent plants.  As bugs and other animals touch a plant, they pick up pollen on their bodies, legs, and antennae.  When they move to other plants, they shed some of the pollen, helping the plants to propagate!

Grow a Bean in a Jar
Materials
A broad bean seed
Jar
Kitchen towel or napkin
Water

Process
1. Swirl a small amount of water around the jar.
2. Fold your napkin and place it in the jar.
3. Place the bean seed in the jar resting on the napkin.
4. Spray some water on the bean every few days.  The bean should start to grow roots in a few days.

What's going on here?
What you are observing is a process called germination.  The water causes the seed to break dormancy and initiate growth.  Bean seeds are relatively easy to germinate, as they don't need much more than water and oxygen.  Other seeds may also require sunlight, specific temperatures, scarification (a weakening of the coat), or stratification (chilling)!