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Activity

Water resistance: racing shapes through water

Summary: 
Move different shapes through water with a weight, to compare their speeds, and so how streamlined they are. Compare to the shapes of animals that move through the water.
Science content (2016 curriculum): 
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Physics: Motion and Forces, Newton’s Laws, Gravity (K, 2, 6)
Science topic (2005 curriculum connection): 
Life Science: Needs of Living Things (grade 1)
Life Science: Animal Growth and Changes (grade 2)
Physical Science: Force and Motion (grade 1)
Lessons activity is in: 
Materials: 
  • tray of water. 5cm deep or more means the shapes do not bump along the bottom too much
  • two medium binder clips
  • fishing line
  • four small binder clips
  • modelling clay, two different colours (one strip from a dollar store pack for each colour; I find about 10-12g works well so that wider shapes do not bump along the bottom)
  • 2 little pots or bags to hold marbles
  • about 8 marbles
Procedure: 

Set up:

Cut a piece of fishing line a little longer than the tray.
Remove one arm (handle) from a mini binder clip, tie one end of the line to its remaining arm, and wrap modelling clay around the body of the binder clip. (Left of first photo.)
Thread the fishing line through the arms of the medium binder clip, then tie the free end to the other mini binder clip.
Attach a little pot to this mini binder clip.
See the first image for the result of these steps. Make two of these for one tray.

Half fill the tray with water, then attach the fishing line/clay unit at one end with its medium binder clip.
Allow the pot of marbles to hang down so that its weight pulls the clay up to the medium binder clip.
See the second image.
Attach the second unit next to the first.

Experiment:

Make two different shapes from two pieces of clay in the same tray.
Pull them both to the end of the tray and release at the same time.
Do several times, to see which shape moves through the water fastest.

Discussion:

In general, wider shapes move more slowly than narrower longer "streamlined" shapes.
Compare to fish shapes: the fish that can move the fastest (e.g. fish that hunt live prey, like salmon) have longer, narrower shapes than those that do not move as fast (e.g. fish that feed on plants or algae).
An image of fish silhouettes is useful for comparing fish shapes.

Notes: 

Visualize using technique in turbulence patterns. Difference between streamlined and non-streamlined shapes.

Grades tested: 
Gr K
Gr 2
Gr 3
Gr 4
Gr 5
Teacher: 
Brenda Koch
Fiona Laporte
Ingrid
Teaching site: 
Aboriginal Focus Elementary
Activity originally developed and delivered: 

Aboriginal Focus School with the Scientist in Residence Program www.scientistinresidence.ca