John,

We would all like to think that we "Teach" with our exhibits. The truth
 is that our exhibits provide an opportunity for visitors to
"Learn", or in other words, teach themselves. When visitors are free to
explore on their own we just can't take all the credit for what they
learn. We only provide the props. Though we hope they learn something,
just what that is is largely up to them. And I kind of like that.

Now when it comes to programs things shift more in favor of teaching, and
that is great too. It is just another kind of learning that takes place, one
that we are  able to understand a little better.

I think you are right about the bind we find ourselves in when it comes
to writing grants. Most of us can be proud of the programs we offer and
be pretty sure that they are affecting people. Few of us come 'clean'
when it comes to exhibits though. We can tell when the exhibits are
"working" its just a little hard sometimes to put a finger on it...

Joe Ruggiero
Director of Exhibits
Flandrau Science Center
Tucson