In this activity, students learn about seed dispersal and make observations of different types of seeds to determine how they travel.

Transcription

1 How Seeds Travel Classroom Activity: K-4 Time: 45-minutes to one hour Overview: In this activity, students learn about seed dispersal and make observations of different types of seeds to determine how they travel. Note: This lesson, How Seeds Travel, is one in a series of lessons introducing basic plant parts and functions. Other lessons cover root structure and function, flower anatomy, movement of water in stems, and breathing or the exchange of gases in leaves. Integration with Project BudBurst Elementary school students participating in Project BudBurst study plants in their schoolyard environment and learn to make careful observations of the timing of leafing, flowering, and fruiting of selected plants. In conjunction with teaching students to make observations of living plants, teachers may also introduce basic plant anatomy, a topic typically covered at this age. The lessons in this series on plant parts and function may be used as an introduction to participation in Project BudBurst, to help set the stage for what students will be observing. Alternatively, teachers may use these lessons in between times students make outdoor observations to extend their understanding of what they are observing. For example, as students observe flowering, teachers may use this lesson Operation Flower Dissection to help students understand the structure and function of flowers. Learning Outcomes: Students will be able to: Describe common ways seeds can be dispersed ( hitchhike, float, be carried by wind). Categorize seeds by mode of dispersal Draw seeds from each category Explain why seeds need to be dispersed. Page 1 of 5

2 Materials: Assorted seeds that travel by wind (e.g. dandelion, western ragweed, maple, pine, cottonwood) Assorted seeds that travel by water (e.g. willow, foxglove, cranberry, coconut) Assorted seeds that travel as hitchhikers (e.g. thistle, cocklebur, crabgrass, beggar-ticks) Magnifying lenses Colored pencils Glue Copies of the How Seeds Travel Student Recording Sheet Education Standards: Available at: Preparation Collect seeds that represent some of the different ways seeds travel. Seeds can be found outside of your school or in your community. Look around trees planted along streets or on school property and around weeds found along the edges of a playground or field. Look for seeds in a wild environment or vacant lot. Many seeds can be found in the fall, so either do this activity in the fall or collect seeds and save them for another time during the school year. Activity 1) Ask students what they know about seeds, and what is the purpose of seeds. You may want to germinate a seed and use it to introduce the idea that seeds grow into plants. Introduce the idea that a seed needs to disperse ( travel ) away from the parent plant so that it will have space to grow. Go over the information provided in the Background Information section on how seeds travel. Discuss that seeds can travel by wind, water, and as hitchhikers on people s clothes or animal fur. 2) Give students an assortment of seeds to look at. Have them use a magnifying lens to look closely at the seeds. 3) Ask students to decide how each seed travels. Have them divide the seeds into groups. 4) Have students record their observations on the How Seeds Travel Student Recording Page 2 of 5

3 Sheet. They should draw the different types of seeds in each category on the recording sheet, and then glue the seeds next to their drawings. 5) Have students share their responses to the questions on the How Seeds Travel Student Recording Sheet. Suggested Extension Activities Observe seeds that travel in the wind. Find two different types of seeds that travel in this manner, hold each of them above your head, and drop them at the same time, or in front of a fan. Time how long it takes for each seed to reach the ground. Which one stayed in the air the longest? Which one traveled the farthest? Drop these seeds outside when a breeze is blowing. Which seed travels the farthest? Collect animal dispersed seeds using socks (with their toe cut out) pulled up over your calf. Walk through a meadow or other vegetated area to see what seeds are collected on the socks. Soak bean and corn seeds overnight. Dissect the seeds to reveal the seed coat, cotyledons/endosperm (food), radicle (root), and leaves. Make a scientific drawing of the parts. For students participating in Project BudBurst, have students collect seeds from their study plant and identify how their plant s seeds travel. Background Information Seeds contain a tiny embryo of a plant inside. The seed halves contain food which supplies energy and materials for growth until the plant grows its first leaves above the ground. Most plants produce a large number of seeds. This is because so few seeds survive. In order to ensure survival many seeds are modified in various ways so they can be carried away from their parent plant. Some fruit and seeds simply drop from a parent plant. They take root there but have competition for space and light. Many seeds have developed wings or silky hairs that allow them to be carried by wind for miles. The dandelion seed, for example, has a little parachute which helps it to be carried by the wind. Seeds from maple trees have wings that turn like a helicopter as the seeds ride the wind away from the parent plant. Many seeds have sharp hooks or barbs which stick to animals with furry coats like sheep or dogs. They drop off some distance from where they grew. These seeds are Page 3 of 5

4 called hitchhikers because they hitch a ride away from the parent plant. Many plants produce fruits which animals eat. Seeds are hidden inside the fruit and pass through the gut of the animal as it can t be digested. The seeds are expelled in the droppings of the animal. Some seeds dispersed in this way can t germinate unless they have passed through the digestive system of an animal. Plants that grow along the banks of streams and rivers often have seeds that will float on water. The seeds usually have tough husks and air spaces in the seed to help them float. The best known seed that floats many miles is the coconut. Seed dispersal helps to prevent too many seedlings from growing in a small area near the parent plant. Those plant species that are able to spread their seeds widely have a better chance of surviving. Student Assessment Suggestions: Teachers may use the How Seeds Travel Student Recording Sheet from each student to assess their understanding, or give them new seeds and have them write a description of how these seeds travel. Alternatively, teachers may have students devise costumes to enact how they might travel if they were a seed. For example, students may use a large scarf or fabric as a parachute, or masking tape for hitchhiking, or water wings to float. Source: Adapted from Primarily Plants, developed by the AIMS Education Foundation in Fresno, California and Teaching Plants from Root to Seed, developed by the Denver Botanic Gardens in Denver, Colorado. This teacher resource was made possible, in part, by support from the National Geographic Education Foundation. Page 4 of 5

5 How Seeds Travel Student Recording Sheet Hitchhiker (sticks) Water (floats) How do these seeds hitchhike? What makes these seeds float? Helicopter (wings) AIR Parachute (hairs) How are these seeds carried by the wind? Page 5 of 5