Your wife should not let the toddler play with such tiny lights. They are likely to be swallowed.

The Countycomm Super Tough lights are ok but you have to remember to press the front edge of the button, rather than the center. Also, they're not waterproof.

The Countycomm $1.00 slide switch lights are easy to operate one handed, though not too waterproof either.

Your best bet may be a CMG O-4, which is large by the standards of these coin cell lights, but waterproof.

Reviews of all these lights are in the reviews section of candlepowerforums.com.