I began by having students make observations about their sprouts, and reminded them to record as much data as possible, including smell, color, texture, and size. They couldn't help but notice "white fuzzy looking stuff that smells like mold."
I explained that because the seeds were watered with plain water rather than the bleach solution, they grew moldy. Then I asked them why anyone would use a seed sprouted at all if they are so prone to mold. They were only able to come up with situations similar to our, studying plant growth, even when told sprouters are sold in garden stores, not just to teachers.
So I asked, "How could you design an experiment to find out?" and gave them time to talk about it in their tables.
After much discussion, charting all of our options, and voting on our measured outcome, we came up with the scientific question "How does the location seeds germinate affect how long they keep growing for?" Height would have been a much simpler outcome to measure, but the student who suggested number of days it grows is very persuasive, and they need to measure plant height anyway to answer the question, so I went with it. The important thing is that it came from them, and not me. We planned our materials and procedures together.
The following day, each table followed the procedures we created together. A few student came up with ways we could control more variable, like adding the coffee filter under the soil, and using bleach solution to water both sets of seeds.
Finally, I had them each write a prediction about the outcome of the experiment, including reasoning. In Student Notebook Sample, I felt this was strong evidence to support their prediction.
I had my students record data from both seeds every two or three days. After about 2 weeks, we moved all the seeds into soil. So far, the seeds from the sprouter are taller and healthier looking than the ones started in the soil My students believe this is because the soil was soaking up all the water, so the beans weren't getting enough. Regardless, they were able to use the scientific process to answer an authentic question, and that kind of thinking my main purpose for teaching science.