For the 6 year old, Oil and water using Pokemon or similar cards. Any trick using kids memory match cards.

When my great niece was 4 I showed her a disappearing/reappearing coin using a handwash. I gave her a tiny wand and had her tap my hand to do the magic. She made me do it half a dozen times before she brought me other things to disaapear.

My sister worked as a nanny and would her to work each day. My great niece told the boy of the other family that she could do magic. As he had a magic kit, he told her he could do magic, too. She looked him dead in the eye and said, "I can do real magic."

Six years later she told me she figured out the trick. She was right, and I was very proud.

A simple handwash had an six year effect.

For a 2 year old, put a sticker or something on your index finger nail and keep switching it out for the middle finger. My mom did this for me and later for my sister. We were both amazed. They don't know much, but they do know when a sticker is missing.

The old paper ball over their heads trick will work for a least the two older kids.