This is my front yard pond. I have two much smaller ones in the back yard garden. When our well pipe was leaking 3 years ago (in the dead of winter) we had to have part of the front garden dug up to put in the new pipe.
When the mess was over we were left with a large flat rock too heavy to move. Solution? Garden pond beneath it. The kids love this. Lill and Quinn spend many a day seaching for bugs, frogs and plant life to investigate. (Here's a post from last spring). Put in a few gold fish to feed and it makes a nice place to sit and watch the birds at the end of the day.
It's really not very big but it's enough to stir the imagination and creativity. Enough to stir interest to learn. Can't beat that - plus it's nice to look at.