a new phrase

Conversational skills are increasing exponentially. When asked today where Froggy was (and I ask this question hundreds of times per week), Dennis replied "I don't know, Mommy, let's go find him." When he spotted him, he announced, "look, Mommy, there he is!! I found it!!". Talking to him is a real pleasure now. We walked tonight with an old friend of mine from high school and he asked her if she liked trains and asked her if she'd seen a train tonight. The track where we sometimes walks borders the train tracks and we always have to stop and watch a train go over the bridge whenever one passes while we walk. I haven't heard him say "I don't know" before, but he told her tonight "I don't know where train is. There's tracks right there. Where's train?".