I saw this idea on the wonderful Facebook group, and I believe it is also on Sugardoodle.
This is an activity better suited for SR primary, not so much for JR primary, as most of those little ones can't read.
First, explain the weird phenomenon of most people being able to easily read a scrambled word as long as the first and last letter are correct. Then split the Primary into 4 groups, by class or area of the room or by counting off or however, and give each group one verse to figure out. (I'm going to give the easier verses, 1 & 4, to my younger kids, and the harder verses, 2 & 3 to the older kids.) Have the pianist play the song softly in the background while they are working. When they are done, have each class come to the front, either by a spokesperson or all together, and read or sing their verse. Then put up a bigger version of all 4 verses and the chorus on the board and sing the whole song through together. This can be a great intellectually stimulating activity for those older kids as they need to really focus on some of those words.
HERE are the verses on individual sheets for handing out to classes.
HERE is the whole song scrambled in large print for posting at the front.