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Natural Science - Year I

Unit 24: Observing Circulation

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Lab: Observation of Circulation in Goldfish

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Natural Science Unit 24 Laboratory Activity: Circulation

Goal: To observe the movement of blood through capillaries.

Materials and Equipment:


  1. Wrap the goldfish in wet cotton, except for the tail.
  2. Place the goldfish in the shallow dish.
  3. Spread out the tail so that it lies flat and put the microscope slide carefully over it.
  4. Observe the movement of the blood through the vessels of the tail. If possible, draw what you see, and record any interesting things you observe.
  5. Be sure to keep the cotton wet with the eyedropper while you make your observations.
  6. Do not keep the fish out of water for more than 5 minutes at a time, or it will die.


Write a short description of your observations. Include drawings if possible.

Can you see individual blood cells moving through the capillaries? Do the capillaries of the tail expand and contract?