Tadpole Tragedy

I'm feeling like a mom failure! The other day I had the brilliant idea to take Brock down to the park by our house and catch some tadpoles from the pond. We spent hours having a grand old time catching them, bringing them home and talking endlessly about how they will turn into frogs - even naming them!! By the way, while I was there many moms were telling me how to "raise" tadpoles, feed them boiled lettuce, etc. I mean what could be more fun for a 2.5 year old - Brock was in heaven. Well, last night when Brock and I went to check on our tadpoles we discovered that they are also in heaven!! To really twist the knife into my chest Brock kept asking, "What happened to my pollywogs Mommy?" I want to sneak down and get more, but I don't want to kill them too. My theory is they didn't like the clean water I transfered them to. I feel horrible - I'm hoping this is not a reflection on my mothering skills - but seriously, how hard is it to keep a few tadpoles alive?! I was hoping this would be a happy post about our tadpole adventure, but so much for that. RIP tadpoles.