For my five year old son we had a Mad Science Party. We actually called it a Magical Science party since we thought the kids would understand that better. So first the invitations. On the computer I printed out from my clip art, a picture of a "magic potion" bottle (like a genie bottle) on white paper. You can also draw this, the shape is pretty easy! To make it look like glass I also cut the same size transparency.  To make it look like it was filled with potion, I cut a piece of colored (I used red) paper 1/2 way down and placed it between the transparency and the white. (Something similar was on family.com) I placed the party info on a piece of rectangular paper and placed on a wooden ice-cream stick. Stuck this inside(like a potion being mixed)between the red and white. The kids pulled this out of the Bottle. I also threw some glitter in there. Then I went to local consignment shops and found button down white shirts for labcoats.  We then made Bunsen Bow ties out of the black foamboard , clipped them on with those black clips, and used Harry Potter glasses. Our little scientists decorated their bow ties with star stickers and gel pens. I just had regular food, pizza and dogs and the cupcakes had star sprinkles on them. I did take the easy way out and have someone come who did create "magical potions" and all kinds of neat things.  The favors were little binoculars and a magic game and they kept their glasses and bow ties.  The boys loved it and the pictures are adorable.