Science Chimps have lots of aquariums and terrariums around all the time.
It took awhile to get the pondlets in balance. Thanks to all the nutrients in the silt (and probably in the goldfish pellets), I had a few weeks of severe algal blooms which I addressed with siphoning and water changes. Because I didn't want to suck up any taddies with the silt, I retrofitted my siphon with an onion bag, doubled over four times and secured with a rubber band. Worked pretty well.
The point being to see the tadpoles growing and changing, or what's the point? Finally, the algal blooms settled down, the water cleared, and we got to enjoy them again. FYI I used only rainwater in the tadpools, just as I do in my Amazon tank. Tap water around here is pretty nasty for delicate aquatic organisms. About the only thing that does well in it is cichlids, which are adapted to its high pH.
As July wore into August, several froglets emerged each day. Such a magic moment, when this creature of water becomes a creature of air; when it switches from swimming with lashing tail to kicking with its brand new hinders. When it crawls out and does its first pushup with brand new arms, looks around and
suddenly lunges forward to nab a gnat.
I saw that, once. Where once there had been a sucker now there was a little frog mouth and it snapped open and the gnat was gone.
Cradled in the water hyacinth, a new frog wonders.
I noticed that the new frogs looked smaller than the tadpoles. They lost their big poochy guts and got waists. Which makes sense, since they're moving from herbivore to carnivore, too, and perhaps need a shorter intestine as an insectivore than they did as an algavore.
This perfect miracle played out each day for us to watch. The kids called the four-legged tadpoles "armies" and kept an eye on them, because they knew once the tads had grown arms that they'd be frogs soon.
Ah, the joy of maintaining a microcosm.