Build the House of the Lord
(by Tammy in Spanish Fork)
You could have two boxes; fill one with sticks or odd shaped rocks, and fill the other one with blocks or bricks.
Then choose three or four children to come up to the front and try to build a house out of the contents of the first box. (Obviously it will not work very well)
Then choose three or four children and have them come up and try to build a house out of the contents of the second box. (Hopefully, if the kids cooperate, it will work much better)
This can lead into a discussion about how we use the very best to build the House of the Lord.
You could show pictures of various rooms inside the temples to give them an idea.
You might also be able to use the song, "The Wise Man and the Foolish Man."