The Pepper Dance

Grade Level: 2

Strand: Understanding Earth And Space Systems

Topic: Air And Water In The Environment

Overall Expectation:

  • investigate the characteristics of air and water and the visible/invisible effects of and changes to air and/or water in the environment

Specific Expectation:

  • investigate, through experimentation, the characteristics of water (e.g., water takes up space, flows or moves when not contained, has mass) and its uses (e.g., living things need water to stay alive; water makes things move: spins a water wheel; water makes certain activities possible: keeps a white-water raft afloat)

Materials Needed:

  • 2 pie plates (pie pans or tins)
  • Cup of hot tap water
  • Cup of cold tap water
  • Pepper shaker
  • Liquid soap in a small jar

Procedure:

  1. Fill one pie plate with hot water and the other with cold water.
  2. Sprinkle some pepper evenly on the water in each pie plate.
  3. Dip the tip of your finger into the liquid soap in the jar.
  4. Slowly immerse that finger near the edge of the hot water plate. Observe.
  5. Repeat steps 3 and 4 with the cold water plate.

Scientific Principle:

The pepper will scatter in the hot water when the soapy finger is placed into the water, while the pepper in the cold water does not scatter very far. The reason for this is that the molecules of the cold surface have greater density, therefore they move less rapidly than the hot water particles, which are lighter. There is surface tension between the water and the pepper, however the molecular structure of the soap on the finger breaks this tension.

Definitions:

  • Density - measurement of mass of a certain volume of a material
  • Surface Tension - the attractive force exerted upon the surface molecules of a liquid by the molecules beneath that tends to draw the surface molecules into the bulk of the liquid and makes the liquid assume the shape having the least surface area
  • Molecular Structure - the location of the atoms, groups or ionsrelative to one another in a molecule, as well as the number and location of chemical bonds

References:

Merriam-Webster. Merriam-Webster’s Online Dictionary. 2010.

Modofacto. Online Medical Dictionary. 2009.

Parratore, Phil. Hands-On Science for the Active Learning Classroom. 1998. Illinois:

SkyLight Training and Publishing Inc.

Ministry of Education. Science and Technology: The Ontario Curriculum Grades 1-8.

2007. Ontario: Queen’s Printer for Ontario.

Other Considerations and Opportunities

  • To see a video demonstration of this experiment go to:
  • Although the first pie plate is filled with hot water, by the time you execute the experiment the water will be warm and there should be no risk of being harmed, however do take caution.
  • Before conducting this experiment, ensure that there are no students with sensitivity to scent (pepper).
  • If you have access to a SMART document camera, this would be an extremely useful tool to showcase this experiment to the entire class as they sit in their desks. If this technology is not accessible, ensure that caution is taken as students gather to view the outcome of the experiment to avoid spilling.

Lauren Roussell

Laura Gurney