In his commentary on Ephesians, William Hendricksen explains:

“The apostle assumes that among those who will be listening when this letter is read to the various congregations the children will not be lacking. They are included in God’s Covenant..., and Jesus loves them.... Were Paul to be present with us today he would be shocked at the spectacle of children attending the Sunday School and then going home just before the regular worship service. He has a word addressed directly and specifically to the children.”(William Hendricksen, Galatians and Ephesians (Grand Rapids: Baker, 1979) pg. 258)