I’m retired now, but for many years in my combined first and second grade, we did some plant experiments with lima beans. Here is my blog about that:

In my combined first and second grades, before carrying out lima bean experiments, planting books were regularly read to the class. There was a thorough review of the required conditions for healthy plant growth – good soil, water, light, and warmth. There was also information about how scientists formed a hypothesis – what they thought would happen and why.

When it was time for carrying out the experiments, lima beans were soaked in water for ½ hour. They loved opening up some of them to see the small plant inside each bean. Then children in groups of three or four planted two lima beans in each of three ½ pint milk cartons. The control plant would be planted in the right condition while the other two would each have one condition changed. They were to decide what the changed condition of their experimental plants would be and the names of all three.

Children wrote a first report explaining the names of the plants, what the changed condition would be, and making their hypotheses. There were ideas on the blackboard to help in writing this report.
Throughout the years there were such a variety of changed conditions. Water and soil were most common using liquids such as sodas, juices, and sauces. Much imagination was used for the planting materials as in assorted cereals, sand, sawdust, styrofoam, peanut butter, and pine needles.
Each group had the items for their experiment listed on a 3”x 5”index card covered with cellophane, with the pertinent information. For example: Silly, Cool One, and Gentle: changed conditions – Silly watered with grape juice/Cool One watered with lemonade/Gentle, the control plant.
Every morning upon arrival, children would scurry over to their experiment to see what, if any, changes had taken place since the previous afternoon. Of course, Monday mornings were most intriguing.

After several or more weeks of observing, final reports were written explaining the results.

Read more about the experiments in my book, Early Childhood Programs: Opportunities for Academic, Cognitive, and Personal Success. Included is a web site where programs can be downloaded for use in a classroom. Also, see 7 reviews on amazon.com