John 3:16 is arguably the most memorized verse in the Bible, and as such, often doesn't get taught as a separate lesson to children in many Sunday Schools. Instead, it is often taught and discussed in other teaching opportunities, such as memorization games and Confirmation class work. As well, Rotation.org tends to collect and create lesson plans about stories and not single verses. That said, we do have some good ideas for John 3:16, and here's one of them in response to member NCSue's request for lesson help.
We doing a unit on Love God, Love People and we started with the Greatest Commandment scripture from Matthew 22:34-39 and then tying other scriptures with it (i.e. I Cor. 13:4-8a). Now, I want to tie John 3:16 to the idea that God loves us so much that He sent Jesus to us.
We did one lesson from the Writing Team's John 3 Nicodemus story to introduce the idea. Other ideas for John 3:16?