How do you get to Heaven?

A week or so ago our fish died. Alex woke up from his nap and asked where the fish went. I really don't know how to explain death to a two year old. I was trying to come up with some deep insight, or maybe a teaching moment to try to explain the Plan of Salvation or at least the after life to a two year old. But I kept it simple and I told him that the fish died and so I flushed him down the potty and that he lives with Heavenly Father now. The conversation went on something like that for a few days. Every so often he would tell me that the old fishie was dead and now he lives with Heavenly Father. Great! He gets it, or at least some of it... then last night I hear him flush and then he comes racing out of the bathroom,
"Mommy, I sent my pee to Heavenly Father!"
Maybe he's not to clear on the idea after all.