-weights+spinning chair from demo day  http://wonders.physics.wisc.edu/spinning-stool-hand-weights.htm
ask someone from the group and sit down of the chair and we will spin them slightly with their weights held tightly to them and then tell the person to hold your arms and the weights out and they will notice that they go faster.

-bed of nails  http://phun.physics.virginia.edu/demos/nail_bed.html

pick one person from the group of people that want to  lay upon the bed of nails and my partner and i will lower them down gently  and then put another board on top, then ask if anyone else wants to do it if there is time. lower them down and explain that if your weight is evenly distibuted among the nails then it should not be painful

   

Step 1:  Pour 1/4 cup of liquid starch into a bowl.  Add 2 Tablespoons of iron powder and stir until well mixed.

Step 2: Add 1/4 cup white school glue and mix.

Step 3: Take the slime out of the bowl and mix with your hands. 

Step 4: Pat the slime dry with a paper towel to get rid of any excess liquid. 

2. Bicycle wheel (from demo day) - The centrifugal force generated from the spinning of the bicycle wheel directs the rotating chair in that direction.  ( https://www.youtube.com/watch?v=1fWl2LNpcak )

3. Bed of nails (also from demo day) - Assuming that the number of nails in the "bed" are numerous enough, the weight of the person should be distributed evenly among each one. In this way, the pressure placed on each nail isn't enough to puncture the skin. ( https://www.youtube.com/watch?v=hG7lGZqWFpM )

coin in the balloon
blow up two balloons and put a coin in one, the balloon with the coin will flale aroud when tossed in the air while the one with out will stay calm
gravity marble
put a marble in a wine glass and start to spin the wine glass, then tourn it upside down, the marble will not fall