Slip on some shades and head outdoors for fun hands-on learning and science exploration.
- Grades: 3–5, 6–8
A Sunny Introduction
Start off your unit with some engaging informational read-alouds, such as The Sun by Dana Rau, The Sun (Eye on the Universe) by Niki Walker, and What Makes a Shadow by June Otani. You might also share some of the many wonderful folktales about the origin of the sun, such as Why the Sun & Moon Live in the Sky by Elphinstone Dayrell or The Stolen Sun: A Story of Native Alaska, by Amanda Hall.
Creating Color Spectrums
Although sunlight looks white, when it passes through water — such as raindrops or a glass of water — it bends and separates into a spectrum, or rainbow, of seven colors: red, orange, yellow, green, blue, indigo, and violet. Invite small groups to create spectrums from sunlight by using clear plastic cups of water and white paper. Have them pinch the cup by the rim, then gently tilt it up and down until a color band appears on the paper. Next, provide different hues of food coloring and have each group predict what will happen if they add the colors to the water. (The bands of color will be altered.) Have groups add one drop of color to each cup.
To extend: Students can vary the amount of water and the size and shape of the cups. Have them write their observations to determine which method cast the brightest rainbow images.
At noon on a sunny day, lead students outdoors to spot some shadows! Have partners observe each other's shadows, measure, and draw them. Later in the afternoon, ask partners to observe, measure, and draw their shadows again, then compare and contrast the midday and afternoon shadows. (At noon, the sun is directly overhead, making shadows appear short. In the afternoon, the sun shines at a lower angle, making shadows appear longer.)
Before clocks were invented, people told time using the shadows made by the sun. Invite students to experience this with their own sundial necklaces. For each sundial, you will need a large plastic lid (from a chip canister or yogurt cup) and a drinking straw. Then follow the instructions below. To use their sundials, students can head outdoors to a sunny spot. Show them how to hold their sundial necklaces parallel to the ground, with 12:00 facing north. The shadow from the straws will show the time on the sundials!
To make each sundial, precut an X in the center of each lid with a craft knife. Poke about an inch of a 2-inch length of straw through the X. Cut several slits in the inserted end of the straw. Flare the sections up against the back of the lid, and tape them in place with clear tape, as shown.
Have students decorate their sundials with a light color acrylic paint (or glue on a paper circle, cutting the center to fit around the straw). Next, have each student mark a line along the side of his or her sundial. Then go outdoors and tape an X in a spot that receives sun throughout the day. Show students how to line up the marks on their sundials to X, then use a permanent marker to mark the rim of the sundial where the straw makes a shadow. Write the number for the hour next to the mark. Repeat each hour throughout the day. Finally, students can cut a slit in the side of their sundials at the center, and loop a length of yarn in it to make a necklace.
Help students compare how materials conduct heat from the sun! Find a glass, plastic, and metal container, each about the same size. Pour an equal amount of water into each. Set in a sunny spot. Ask students to predict which container will heat the water the fastest. Next, have them measure the temperature in each container and log it on a worksheet. Repeat this step every hour or so. Later, have students compare their temperature readings for each container, and create a class graph of the results. Were their predictions correct?
To extend: Have students predict which will happen to the water if left in each of the containers for an extended period of time. Then mark the water line on each container and place them in a sunny area where they can remain undisturbed. Ask students to check the water level daily. What happens to the amount of water in each container? Will the water evaporate from any one container faster than the others? If so, which container? Why? After observing the actual results for several days, explain that the sun plays a major role in evaporation of water in the water cycle. Later, the evaporated water will form into drops and fall to the earth again as rain.
Safe Sunbathing: Comparing SPFs
Too much exposure to the invisible, ultraviolet rays of the sun can cause sunburn, wrinkles, and skin cancer. We wear sunscreen to protect our skin from these harmful rays. Invite students to compare the protective properties of sunscreens with different levels of Sun Protection Factor (SPF) with this fun classroom experiment. First, have each student cut one large "gingerbread" person out of dark construction paper (blue, purple, and red work best). Ask students to coat the head, arms, and legs of each of their shapes once with sunscreen, using a different SPF for each part. Have them label the parts with the SPF used. Set the shapes in direct sunlight for several hours. What happens to the unprotected parts of their shapes? Why? Which SPF gives the most protection?
Sunlight Growth Experiment
Sunlight is essential for all growing things to thrive. To demonstrate, have students plant fast-growing seeds in three separate pots. Set the pots in an open, sunny area. Then place a large dark bucket or container over two of the pots. Have students check, compare, and discuss the growth of the plants daily, replacing the bucket over the two pots after each observation. Have students record their daily observations on a chart or science log. (Be sure to water all plants as needed.) Do the plants grow at different rates? Why? (The plants will grow at about the same rate until they sprout. The plant receiving light will begin to grow faster because the light helps the plants photosynthesize, or make food.) A week or so after sprouts appear, remove one bucket and expose the pot to sunlight. What happens to the growth of this plant? (It will respond to light and begin to grow at a faster rate.) What do students think will eventually happen to the plant under the bucket? (It won't thrive, and will soon die.)
Demonstrate the incredible heat of the sun by building solar kilns! For each kiln you will need a shoebox with a hinged lid (or use tape to attach the lid to a regular shoebox). Have students line their boxes with foil, shiny side out. Next, give them modeling clay from which to create sun-shaped medallions (to use as bead necklaces or fridge magnets). Set the kilns in the sunlight, propped open to reflect the sun's rays. Have students put their clay decorations in the center of their kilns until they are baked dry. Explain to students that the foil captures heat from the sun to “bake” the clay.
Invite your students to create their own sun-safety tags! First, have students brainstorm some sun-safe behavior, such as:
- Wear sunglasses.
- Rub on sunscreen.
- Put on a hat.
- Wear long sleeves and pants.
- Play in the shade.
- Be sun-safe even on cloudy days.
Next, invite students to list the safety tips they´ve come up with on sun-shaped cutouts. After reviewing all the tips, encourage students to attach their tags to suncreen bottles, beach bags, beach chairs, picnic baskets, playground fixtures, and elsewhere, as reminders to protect themselves from the sun.