Here are some resources and ideas for working with seeds in your classroom

• Seeds

• Equipment for germinating seeds and growing seedlings

• Looking at small seeds and seedlings: Magnifiers and Videoflex

• Seed images

We use a variety of seeds during this unit. Students can contrast seeds of different types and sizes. In the seed bags (a lesson based on SCIS curriculum), we use fairly large seeds that have contrasting features and growth patterns. The students plant corn, bean, pea, and squash seeds. Corn is a monocot (has a single cotyledon) while the others are dicots (have two cotyledons). Bean and pea have storage cotyledons while in squash, the cotyledons are leaf-like. In bean seedlings, the cotyledons are held on the stem above ground, but in peas the cotyledons remain underground. There are many other differences in leaves, plant form, etc. which students can observe and compare.

For dissection, we use giant lima beans, other beans and peanuts. Dried beans should be soaked for about 10 hours before students open them. Seed features, especially the plant embryo, are easily observed in these examples.

We use seed mixes (like wildflower mix) and assorted seeds to observe germination in small and large seeds, seeds of different colors and familiar vs. unfamiliar seeds.

To study the numbers of seeds in fruits, we use squash and cherry tomatoes. We tried using peas, but found that, because there are fewer seeds in each pod, there is less variability in seed number from pod to pod. The lesson is more interesting and challenging when using fruits with larger numbers of seeds.

We germinate Wisconsin Fast Plantä seeds and/or radish seeds on water agar plates. This allows students to observe stages of germination they have not seen while growing Fast Plants in soil. In particular, this is an excellent opportunity to see root and root hair development.

For the seed bag lesson, we use small Ziploc® bags filled with coarse, light-colored vermiculite. This material allows students to separate the seedlings from the growing medium. We recommend hanging these on a rack near a window. Bags taped to windows in our classrooms probably got too warm in direct sunlight and too cool at night. This led to problems for seed germination and seedling survival.

To observe the early stages of germination, you can use moist paper towels instead of vermiculite. Large seeds should be soaked for 8-10 hours, then placed inside moist paper towels in a plastic bag. Smaller seeds may not need soaking. If mold appears, the bags should be discarded.

To observe the growth of small seedlings, and to carry out experiments on seed germination, we also use water agar plates. Agar (approx. 1/4 cup) and water (1 liter) are mixed, boiled and poured into Petri plates. After a few hours, the liquid hardens and seeds can be scattered on it. For small seeds, the water agar will provide enough moisture for germination. Larger seeds may need to be soaked first. On this clear medium, changes in the seeds and seedlings are easily observed.

To observe later growth of roots, we also use a Root View® planter, available from NASCO. The planter has angled clear Plexiglas® sides. If seeds are planted very close to the side of the planter, much of the root system will be visible when the plant has developed.

We highly recommend that you have magnifying lenses, a stereo microscope, and/or a Video Flex® camera in your classroom during the seed unit. Many of the details of germination and growth will be missed without this equipment. The Video Flex® is particularly useful because the image from it can be shown on a TV monitor or computer.

We have photographed many seeds and seedlings at different stages of development, using a Video Flex® camera (or stereomicroscope) and image capturing software.

Additional useful images and posters are available through Seed Savers Exchange or other gardening or scientific supply companies.