Sinking And Floating

Tunya Alexander                Frank L. Gillespie School
                               9305 S. State St
                               Chicago IL 60643
                               (312)535-5065

Objectives:

The mini-teach is adapted to grade levels 3-6 and special education.
The main objective of the mini-teach is to explain the Archimedes' Principle, 
which states that any body completely or partially submerged in a fluid at rest 
is acted upon by an upward force.  The size of the force is equal to the weight 
of the water displaced.  Using this principle, students would be able to tell 
why some things sink and float. 

Materials Needed:

Materials per students
A.  Deep-water diver                         
    1. plastic pen top                          
    2. 16oz. of water
    3. modeling clay
    4. 16oz. clear plastic bottle

B.  A Cartesian Diver
    1. 16oz. plastic bottle 
    2. 1 drinking straw
    3. 1 bottle top full of modeling clay
    4. 16oz. of water

C.  Pushing Water with Different Coins
    1. 1 small glass 
    2. tap water 
    3. several types of coins
    4. 1 marker

D.  Floating Boat
    1. 20 paper clips 
    2. aluminum foil
    3. ruler
    4. bucket of water

Strategy:

A.  Deep-water diver
    1. Stick a small piece of clay onto the pen top.  This is the diver.
    2. Put the diver into a glass of water.  Remove or add modeling clay until 
       the diver floats upright.
    3. Completely fill the bottle with water.  Put the diver in and screw the 
       top on tightly.
    4. Squeeze the bottle and the diver will float up and down.

B.  A Cartesian Diver
    1. Fill a plastic bottle with water right to the top.
    2. Make a diver from a straw, paperclip and clay.  Cut the straw 2 inches
       long, open up a paperclip, take the straw and put it on each end of 
       the paperclip, apply clay round the end of the paperclip. 
    3. Test that it floats in a glass of water.  Add clay until it only just 
       floats.
    4. Once the diver is just floating, put it in the bottle of water.
    5. Screw the top on the bottle.
    6. Squeeze the bottle gently.  The diver should sink.  Stop squeezing the 
       bottle and it should rise.  A diver like this is called a Cartesian     
       diver.

C.  Pushing Water with Different Coins
    1. Fill the glass with water so that water is about 1cm from the top.
    2. Draw a line on the glass at the top of the water.
    3. Slowly drop one penny at a time into the glass.  Keep adding pennies 
       until the water spills over the edge.
    4. Pour out the water and count how many pennies you used.
    5. Fill the glass again to the same line.
    6. Slowly drop nickels or dimes or quarters into the glass until the water 
       spills over.
    7. Pour out the water and count the coins.

D.  Floating Boat 
    1. Cut 2 - 30cm squares from the aluminum foil.
    2. Wrap one of the metal squares around 10 paper clips and squeeze the foil 
       into a tight ball.
    3. Fold the four edges of the second aluminum square up to make a small 
       square pan.
    4. Place 10 paperclips in the metal pan.
    5. Set the metal pan on the water's surface in the bucket.
    6. Place the metal ball on the water's surface.

Performance Assessment:

The students will be able to answer the following question using Archimedes' 
Principle:
1.  Why do some objects sink?
2.  Why do some objects float?
3.  What happens when light objects are placed in water?
4.  What happens when heavy objects are placed in water?