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Bronxville Union Free School District

Eighth-Graders Perform Lab Experiments During Annual “Sludge” Test

Bronxville Middle School eighth-graders performed a series of laboratory experiments that required them to separate different substances during the annual “sludge” test, a tradition at the Bronxville School for more than 40 years.

At the beginning of the weeklong collaboration, the students received a sample of “sludge,” which contained a mixture of liquid and solid components. They were tasked with separating the substances in their sample and employed a series of techniques to determine the characteristic properties of each pure substance, including boiling point, freezing and melting point, density and solubility.

“Some of the techniques they used are fractional distillation, filtering and straining, evaporating liquids and water displacement,” science teacher Jean Windels said. “We used temperature probes and a computer program to monitor the boiling points as well as lab equipment that the students chose to use.”

At the end of the experiments, the students in Windels’ and Jennifer Zopp’s science classes submitted evidence of their conclusions in the form of calculations and graphs.  

“They came up with their own plan and procedure for tackling the problem,” said Windels, who added that the project fostered the students’ critical thinking skills and allowed them to engage in self-directed learning. “They also kept a journal of their thoughts and ideas as they proceeded through the week.”

  • Bronxville Union Free School District - Image
  • Bronxville Union Free School District - Image
  • Bronxville Union Free School District - Image
  • Bronxville Union Free School District - Image
  • Bronxville Union Free School District - Image