Anticipatory Set
 

Discover: "How Slow can it Flow?" p. 28 M

Items used:

Honey,

Paper plate

Writing utensil

Masking tape

Procedure: Follow steps in the book on p. 28 M.
Refrigerate honey if possible
Divide the class by sides have a contest honey vs. molasses.

Assign Reading

Go over "Guide for Reading" and "Reading Strategies" p. 104K

• Relate the theory of plate tectonics to the movement of Earth’s continents.

Show the class a map of the Atlantic Ocean. Use a map with a continental shelf showing. Show how they fit together like puzzle pieces.

• The Earth’s surface or crust is made up of plates like pieces of a broken egg shell
• The edges of the plates are actually cracks in the Earth’s crust.
• Theory of Plate Tectonics: scientists have a theory that these plates are moving slowly in varios directions.
• Some plates are moving away and some plates are running into each other and some plates are sliding side by side.


How Fast do Plates Move?

• These plates are moving very slowly.
• Small plates move several centimeters each year, others only millimeters.
• By knowing the plates average speeds scientists can see how far they have moved in the past and simulate what the earth may have looked like before.
• Scientists can also project ahead what the earth may look like in the future.
• See figure 8 pp.30-31
• Calculating distance: Once you know how far a plate moves each year, you also know the speed. If a plate moves 5 cm each year it’s speed is 5cm/yr.
• With this speed we could calculate how far it would move in 1,000 years.
• EX: speed = distance/time Distance = speed x time.
• This can then be converted to meters.
• Converting Units: how would you determine the distance each year? You would need a conversion factor. How many days are in a year. 365 days/ 1year or 1 year/ 365 days.
• Now to convert to days we want to cancel out years. 5cm/ year x 1 yr/365 days. Years cancel out and everything else multiplys. = 0.0137 cm per day or 1.37 mm each day.

See page 29 M for directions.

Notes: convert units so that they are all the same.

Extra: ask them to calculate how far they would move at 4 cm/yr for 8,000,000 years. What would that be on kilometers.

Science at Home:

On page M 31 there is an activity to do at home with your family.

Hints: Get at least two other family members of different ages.

Measure more than one nail in case one breaks.

Calculate how long they would be if you let them grow 1 year.

Assignment:

Handout review and enrichment handouts