In this department we've provided lots of goodies to explore this exciting subject.  The Science Kits provide an elementary level introduction.  The apparatus and demonstrator kits are great for middle school, high school and college.  Some have been difficult to categorize, so we recommend that you browse all the pages as something may be listed other than where you might think it would be. 
Science Kits
Science and activity kits for individuals and classrooms.  Start at pre-school level and advance through elementary, middle school and high school.
 Pressure
Apparatus for demonstrating basic principals of pressure.  Excellent for middle school through college.  Includes Pascal Vases, Pascal ball,  Boyle's Law Apparatus, Venturi Apparatus, Pressure Syringe and Manometers.  Everything but a squirt gun.
Hydraulics
Hydraulic press and hydraulic turbine model.
 Vacuum
The famous Magdeburg Hemispheres dramatically demonstrate the power of a vacuum as well today as they did 400 years ago. Also great guinea feather apparatus to show effects of gravity in a vacuum.
Current, Convection
Liquid Convection Apparatus, Gas Convection Apparatus and Secchi disk
Specific Gravity
Density cylinder Sets, Specific Gravity Blocks, Overflow cans, Archimedes Bucket and Cylinder, and Archimedes Principal Apparatus
Density
Closely related to specific gravity.  Hope's Apparatus, Density Ball, Air Thermometer Bulb and Liquid Expansion Bulb.
Capillary Action
Equilibrium Tubes and Capillary Tube Set
Pumps
For use with various experiments and activities
Fun with Fluids
Make learning fun with these great gadgets.