To allow students to design seed investigations based on questions generated late in the unit. To develop and assess students' understanding of inquiry.

Investigations included studies addressing questions like:

• Do fast plant seeds grow on different surfaces: soil, agar, or sponge?

Students wondered whether seeds like Fast Plants would grow in or on materials other than vermiculite. Addressing these student questions, we tested whether seeds germinated on a wet sponge, on an agar plate, and in soil watered by wicking from a reservoir.

• How do roots grow and develop?

Students found it difficult to observe root growth in the seed bags. To help students observe the root systems of various seedlings, seeds were also germinated on agar plates. Many students were surprised to find seeds grew quicker on plates than in soil. They were interested to observe changes that normally happen underground. Students were able to see the roots and especially root hairs more clearly on agar than in vermiculite. One teacher placed four corn seeds, oriented in different directions, on individual agar plates stored vertically, so students could observe how roots develop when seeds are in different positions. In another trial, a seed mixture was germinated on agar, and students could compare seedlings of different plants.

• Do seeds sprout and do plants grow in the dark?

In this investigation, students germinated seeds under dark and light conditions (in a covered box in a dark cabinet vs. on a windowsill) and compared the growth of the seedlings. While planning this investigation, the class discussed how they would design a "fair test" of this question. They used wick watering systems to make sure that plants under both conditions had the same amount of water. Students insisted that all light be excluded from the dark condition, except, of course, for the times the plants were observed. Because students did not consider controlling other factors in their experiments, these discussions were useful in designing this particular study as well as learning more general principles of experimental design.

• Do Indian corn seeds grow?

• What do the plants look like?

• Do seeds soaked in salt water grow well?

Student's illustration of results for experiment comparing plants grown in dark and light conditions. The plants are shown on wick watering systems.