Buddy classes
Here are some things I did with a 4th grade/1st grade buddy class:
--type up the directions for an art activity. The 4th grader must read the directions to the 1st grader but is not allowed to do any of the cutting, glueing, etc. After the 1st grader completes his project, the 1st grader tells the 4th grader what to do and the 4th grader is to follow the oral directions. A good reading comp for 4th, good sequencing for 1st, and a lot of fun for all.
--jump rope. The 4th graders learn some jumprope jingles ahead of time, then we all go out and they jump with their buddies. It was great because a lot of the 4th graders really needed the jumproping as much as some of the 1st and this gave them a way to participate that wasn't demeaning
--Thanksgiving feast. The 1st graders were the indians (they had prepared paper sack vests, headbands, and sliced turkey sandwich meat and bread slices into various fractional parts( 1/2, 1/4, etc) The 4th graders were the pilgrims and had made paper hats to wear. Each grade performed little songs and poems, and the 4th graders brought Thanksgiving books they'd written about their Pilgrim voyage to read to the 1st graders as well as some food items they'd prepared for the "feast"