NATIONAL WILDLIFE FEDERATION ARCTIC Summer Midnight Sun Summary ✔ Copies of student worksheets year, as the earth makes its orbit Students build a three- around the sun, the tilt produces dimensional model of the variable day lengths, and the rotation of the earth to change of seasons. When the appreciate the extremes of Background arctic is tilted away from the sun, daylight hours at different The Earth’s axis is an imaginary in the winter months, it gets little months of the year, and make line through its core, connecting or no sunlight. The sun appears connections between available the North and South poles. The to be at a very low angle on the sunlight and the growth and earth revolves around this axis, horizon, which also means less behavior of plants of the arctic. one full revolution per day. The intense light reaching the arctic. earth rotates so that during the On the other hand, when the Grade Level arctic is tilted toward the sun, in 5-8; 3-4 day we face the sun, and at night the summer months, it gets more Time Estimate we face away from the sun. one to two class periods. Because the earth is round, parts intense sunlight almost around the clock. Subjects: of it are closer to the sun than math, physics, geography, others. Parts that are closer Sunlight is critical to photosyn- science (nearer to the equator, lower lati- thesis, the process by which Skills: tude) experience more intense plants produce their own food. analysis, application, sunlight than parts that are Plants need water and sunlight in comparison, problem- further, such as the arctic at high order to photosynthesize. solving latitude. To complicate matters Adequate light and thawed water Learning Objectives further, the Earth’s axis is at a are only available for 3-4 months Students will be able to constant tilted angle of 23.5 ✔ a year in the arctic. The growing Demonstrate how the tilt of degrees. Over the course of a the earth and its rotation affects day length in the arctic (and seasons around the world). ✔ Explain how day length and available solar radiation influ- ence survival strategies of plants native to the arctic. Materials: ✔ Globe, flashlight, modeling clay, scissors, glue, Styrofoam balls and toothpicks—enough for four small and one large ball for each student and five toothpicks for each student, pencils or pens. SUMMER MIDNIGHT SUN www.nwf.org NATIONAL WILDLIFE FEDERATION ARCTIC season is only about 50-60 days. Photosynthesis Because plants are at the bottom of every food chain, sunlight is critical to all life. WATER SUN Plants and animals of the arctic, where available sunlight is highly CARBON DIOXIDE variable throughout the year, have adaptations which help them cope with this challenge. Most plants and animals hibernate or become dormant in the winter. Some animals migrate in the WATER winter to warmer areas south of the arctic circle. Plants and OXYGEN animals take advantage of the summer with a burst of growth or SUGAR activity during this time. For example, during the summer model showing the position of growth during the short animals can eat throughout the the earth relative to the sun at summer, while they are day and night, helping their four different times of the year in dormant in the long winter. young ones grow as quickly as order to understand how this People require sunlight too. possible before winter comes and affects daylight hours and seasons Vitamin D, essential to our the land freezes over again and in the arctic and in other parts of bodily functions, is manufac- becomes dark. This period also the world. tured in the skin when it is helps many animals accumulate exposed to sunlight. blubber, a layer of fat that helps 2. Have students research how keep them warm and provides many growing days there are in them with energy reserves during Procedure your community. (This infor- the long winter months. 1. Why is sunlight important? mation may be found in a Emphasize to your students, that Have your students think farmer’s almanac.) Compare plant life all over the world is about why plants and animals, the findings to the number of affected by both the length of including people, need growing days on the arctic light and the strength of light that sunlight. Discuss photosyn- tundra. How does this differ- reaches the earth, wherever they thesis as the way plants make ence affect the plants that grow may be. their own food, and note that in your area vs those that may In this activity, your students will plants need sunlight in order grow in the arctic? Have construct a three-dimensional to photosynthesize. Arctic students brainstorm plants have a burst of rapid hypotheses and conduct SUMMER MIDNIGHT SUN www.nwf.org ARCTIC NATIONAL WILDLIFE FEDERATION research to test their earth around the sun. One To be sure this activity is hypotheses. student, or the teacher, should carried out correctly, attach a sit in the center of the circle small stick to the globe at the 3. Look at the climate data holding a flashlight, repre- north pole in line with the provided. How many months of senting the sun (make sure you earth’s axis. Tilt the globe the year is the temperature above have turned off the classroom approximately 23.5 degrees freezing in the arctic? Make lights). The flashlight should and choose a stationary object sure the class understands that be pointed directly at the globe in the room (probably on the this is when snow and ice as it is passed around the circle. ceiling) to which the stick thaw, making water available points. No matter which for plants and animals to use. student is holding the globe, In addition to sunlight, water the stick should always be is also necessary for plants to When the Arctic is pointing to the stationary photosynthesize. tilted away from the object. Students in the four 4. Using the data provided on sun, in the winter seasonal positions can attempt Seasons Around the World rotating the globe, maintaining worksheet and the incomplete months, it gets little a constant tilt, to see where graph provided, have students or no sunlight. sunlight would hit over the label the x and y axis and plot course of one day. the average number of daylight 8. Have students label the appro- hours per day in Alaska for 7. The teacher should designate priate seasons on the work- each month of the year. four students equally spaced as sheet. 5. Check your local newspaper or the four seasonal months: search on the internet to find January, April, July and Alternate Method the time of sunrise and sunset October. Using a plastic inflat- 1. An alternate activity is to create and the average number of able globe, students hold the a three-dimensional model to daylight hours for your town earth at its 23.5 angle of tilt study the earth’s position rela- or others with a latitude and pass it around the circle, tive to the sun at four times of between you and Alaska. noting where the sun strikes at the year, each of the four What did you discover? What different seasons of the year. seasons. Students will simulate does it mean? If you find infor- where the sun’s rays reach the mation for several places, you earth in January, April, July, can graph the range of daylight and October, taking into hours for comparison. consideration the earth’s tilt. 6. Have students sit in 2. Use small round objects a large circle repre- for the “earths,” senting the move- such as Styro- ment of the foam balls or SUMMER MIDNIGHT SUN www.nwf.org NATIONAL WILDLIFE FEDERATION ARCTIC small fruit. Students should 23.5° angle and not moving day at that time of year. insert a toothpick through the the paper at all, students Students should notice their center of each of their four should begin an orbit around arctic tundra being at different earths, from “pole to pole.” the sun, being sure not to locations relative to the sun Using a pencil or pen, draw a rotate their earth or change the throughout the year. circle around the North Pole to angle in any way. Secure the 6. Have students refer to their represent the Arctic Circle. second earth to the paper. Do graph of daylight hours and Make another mark on the the same for the third and think about which angle of circle to represent the location fourth earths, again being sure rotational tilt the earth would of the arctic tundra. Use a not to move the paper, rotate be in during each of the four larger Styrofoam ball to repre- the earths, or change the tilt in seasons. Students can label the sent the sun. Insert a tooth- any way. When the model is seasons on their model. pick into the “sun” just far complete, students should Conduct a class discussion enough to secure the ball to check their work by verifying about what their models mean. the toothpick. that the angled toothpicks are Where are the longest days in parallel to one another, all 3. Press five pieces of modeling June? In December? Why does pointing in the same direction. clay onto a piece of cardboard, the arctic have such long days Students can very carefully one in the center for the sun, and short nights and vice versa? rotate each earth without and the remaining four at Why does it have such a short removing them from the clay, equal distances away from the growing season? What do you to see how much sunlight sun, and from each other, think these events mean for might reach their tundra in a approximating a circle.