Look at the illustration of four letters from the American Manual Alphabet. Decide whether the description of the letter is a good definition. If not, choose a counterexample.
The letter I is formed by sticking up the smallest finger and folding all the other fingers into the palm of your hand with the thumb folded over them.
The letter J is a counterexample

The letter y is a counterexample

The letter A is a counterexample

This is a good definition
while keeping your hand still