This idea was another one adapted from another singing time blog (it was so long ago, I can't remember the source). This was a review for primary program songs and also a way to learn a few more "little songs" (that the presidency wanted to throw in last minute-I really try to be accomodating.)
SO I made the solar system out of poster board and each one represented a song from the program. It's hard to see from the pictures, but all of the large planets have little flags on them with the letter "p" for primary. THese planets are ones that we have claimed with our flag because we know the corresponding song pretty well.
So to begin this activity I told them how much I had enjoyed flying all over the universe with them and visiting all these different planets and sticking our flag in them, but we still had a few more planets to visit that don't have flags. They are called dwarf planets because they are very small and the songs on them are very short and easy to learn. For this activity, I also had a little laminated rocket ship that we moved from dwarf planet to dwarf planet as we learned those little songs. And we also added a "p" flag to each of the little planets as we mastered them.
One thing that I added for Senior primary was some decoding. I thought it would be fun to pretend that one of the new songs we were learning needed to be decoded because some of the words were in a weird alien language (going with the whole outer space theme). So I gave them each a piece of paper and pencil with the words to the song. The fun was that the key words to the song were changed to wingding font. Using the key, also on their paper, they had to decode these words. Once they did, they had all the words to this new song right in front of them, so they had no excuse not to sing along.