I recently read an experiment from a science book for elementary school students. Basically, it asks students to compare the loudness of sound produced by shaking the small plastic bottles containing different amount of red beans. There're altogether 4 plastic bottles, filled with red beans to 1/4, 1/2, 3/4, 4/4 of the volume of the bottle. Each bottle is then shaken with the same "amount" of energy (e.g. 3 times), then students are asked to compare the loudness of the sound produced. What do you guys think? Which of the bottle will produce the loudest sound? Actually, do you guys think this experiment makes sense scientifically? Thanks a lot.