This is a great introductory experiment on measurement and experimentation. It uses concepts like CM, ML, G, water displacement, and many more. It has a data table for students to record their results and guiding questions throughout the experiment. Step by step procedures for students are included. Also included is a materials list and teacher notes, with an answer key. I would use this near the beginning of the school year to help build relationships and good lab techniques.
There is a part of this experiment where the beans soak overnight. So it is about a half an hour project on two days (about one hour total)