• Title:
  Penny Lab-An investigation in experimental design
• Time span:
  3 days
• Brief Description:
  Students determine how many drops of water will fit on a penny before it spills over the edge. Students will compile classmates' data and perform a statistical analysis of the data.
• Objectives:
  • Students will design and perform an experiment.
  • Students will collect data and perform statistical analysis including graphs of the data collected.
  • Students will be introduced to variables and controls.
  • Students will write an electronic lab report.
• Materials:
  • Pennies
  • Eye Droppers
  • Cups
  • Water
• Procedure:
  1. Pose the question "How many drops of water do you think you can place on the surface of a penny?" to your class.
  2. After briefly discussing the different answers to the students predictions pass out the materials and instruct the students to investigate how many drops of water they can place on a penny before it spills over. Students should record the number of drops they are able to fit on the penny. (Note: I do not give my students any controls when doing this experiment. I do encourage them to do multiple trials and calculate an average of the trials.)
  3. After the students have compiled their data write their answers on the chalk board or overhead projector.
  4. Students should use the class results to create a summary table of the data. I have them include the following: trials or number of data points reported, maximum number of drops on the penny, minimum number of drops on the penny, range, and average.
  5. After a brief analysis of the data students like to point out that the data is very inconsistent and that some groups must have cheated. This is a great opportunity to introduce controls. Define what an experimental control is and give an example such as on which side of the penny (heads or tails) were the drops placed. Solicit other controls from the students and write these on the board.
  6. Students at this point write an electronic lab report using a ClarisWorks template. As part of the report, students create a line graph of the data points (trials) versus the number of drops and answer discussion questions.

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