BRYAN EATON/Staff Photo. Rachel Casson drops a Sweetheart into ginger ale to see if it floats or sinks, after trying the same experiment in water, as Sophia Perrin, left, and Piper Herndon, all 6, look on. The Valentine candy sank both times. The students in Mary Ellen Hoiseth's class at the Bresnahan School were doing experiments on density and water displacement and her son-in-law, Tom Branon, a microbiologist, made a visit to help with some of the experiments.

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