Submarines

Here are two activities to do featuring submarines that stack together nicely...

A Banneker classic is the "Pen Cap Submarine."  Ever wondered how to do it?  Well, you're in luck...

because I made this video explaining to you how to do it...

A good challenge to spice this activity up a little bit would be taping two lines around the bottle about 3 inches apart and having a contest to see which team of two could design a pen cap sub that could be controlled well enough to hover between the lines for 10 seconds (like the flinker below).  You could also create a series of tasks for the submarine to complete to make it even harder such as
#1 dive to the bottom and stay for 5 seconds
#2 surface at the top for 3 seconds
# 3 dive to between the lines
#4 surface again
#5 hover between the lines for 4 seconds
#6 touch the bottom

Then time the teams to see who's sub can complete the set of tasks in the shortest possible time.

This experiment teaches the concept of Volume very well.

Volume is the space taken up by a substance.

When you squeeze the bottle, you create pressure inside the bottle AND inside the pen cap.  The VOLUME of air inside the pen cap shrinks and the pen cap sinks to the bottom.  When you release the bottle the VOLUME of air expands and the pen cap rises.

Important question - When you squeeze the bottle, is there less air in the pen cap?

NO!  The amount of air stays the same!  You know this because when you release the bottle the pen cap rises.  You didn't put more air in to make it rise again did you?  The amount of air stays the same.  The amount of space the air takes up changes, its VOLUME.

Other important concepts

Pressure - A force squeezing on a substance.

Equilibrium - equal distribution of forces or a situation where forces cancel each other out.

Have the kids draw a diagram like this one to explain how the different concepts work together to drive a submarine.

The next activity is a true challenge which teaches similar concepts...

Flinker Lesson Plan on PBS Zoom

Follow the link and watch the video.  This is a great challenge and can be pretty difficult to figure out.

Use packing peanuts, paper clips and pickle jars full of water.

Stop periodically and ask what problems are the kids having then make a tee chart with problems on the left side and technological solutions on the right.

Problem/Solution
It floats/add paper clips
It sinks/remove paper clips
the peanut falls apart if you put too many paper clips through it/Paper clips can be linked together
It floats until I add this one paper clip, then it sinks/squeeze air from the peanut/remove foam
etc, etc.

BUT make sure to let them generate the problems and solutions as the figure out the activity.

A great concept to teach in this lesson is UNITS

Each paperclip is a unit.  A fixed amount of weight.

1. any division of quantity accepted as a standard of measurement or exchange; "the dollar is the United States unit of currency"; "a unit of wheat is a bushel"; "change per unit volume"

But the units are too large.  If you add one to many the flinker will sink, if you take it off, the flinker will float. You need a smaller/more exact measure to change the buoyancy of the flinker like removing tiny bits of foam or squeezing tiny bits of air from the peanut.