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Activity

Fat test for keeping warm

Summary: 
Glove coated with fat is dipped in cold water, and compared with an untreated glove.
Science content (2016 curriculum): 
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Lessons activity is in: 
Materials: 

For each student:

  • Finger cut from a disposable glove
  • Finger cut from a disposable glove, coated with vaseline
  • Recording sheet

For each table group:

  • Bowl of iced water
Procedure: 

This activity needs adult assistance.

Students put one index finger in a cut off glove finger, and the other in a glove finger coated in fat (vaseline).
Ask: If we put them both in some iced water, which do you think will stay warm longer?
Record your prediction. (see notes below)
Students put both fingers in the water, and wait until one feels cold. They record which stayed warmer longer.
Ask: Why do you think you kept warmer with the fat?

Relate to a bear, if relevent: When bears hibernate, and the temperature outside is really cold (way colder than this water), how can bears use fat to stay warm? They have a layer of fat under their skin.
Feel your fat under your skin by pinching your skin. Your fat is less than a cm thick. Black bears have a fat layer about 4cm thick. Polar bears have a fat layer up to 11 cm thick.

Measure the temperature of the ice water. Winter temps can go way lower than this.

Notes: 

For grade 1 and 2 students the prediction did not work well. Students were more concerned about predicting correctly than in observing what happens. Some made up what they observed in order to make their prediction correct.
For this age group, stick with just observing, or do a group prediction where students do not know what others predicted (students raise their hands while voting for each outcome, and total votes are recorded on the board).

Try crisco, and double layer of baggies: https://www.youtube.com/watch?v=8I96BzSNNqE

Background information: Conductance of heat is about half as efficient through adipose tissue as through aqueous tissues such as muscle. However, such passive properties are probably much less important to thermal insulation than counter-current systems of blood vessels, and control of the rate of flow of blood through the tissue, that brings heat from the warm core to the surface. Blood flow through the superficial adipose tissue can be reduced almost to zero for hours without damaging the adipocytes

Grades taught: 
Gr 1
Gr 2
Teacher: 
Anke Barabulea
Ingrid
Teaching site: 
General Gordon Elementary