If they are younger kids I might use Acts 16:31.
They replied, "Believe in the Lord Jesus, and you will be saved – you and your household." (NIV)
But the one that stood out to me and I remember memorizing is Acts 1:8.
"But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth." (NIV)