After a quick review of the colors in the rainbow and a project demo, I asked students to take one strip of each color and a pair of scissors. To save time, I pre-cut wide strips, four each from a sheet of construction paper. The students cut those strips in half lengthwise and then cut small squares from each strip.
Most students were very self-directed during this project. For those with questions or who got off track, problems were easy to resolve with either quick guidance from me, or a prompt to ask a friend for help.
When finished cutting, students were asked to put away their scissors, grab a bottle of glue and begin constructing the rainbow. I left a couple of examples around the room as a reminder. Some students used too much glue. I think until first grade, that's just how it is. They receive a gentle reminder on how much glue to use, but when they come across a bottle that squeezes easily, they're so excited that they squeeze it everywhere. It's okay though, as the children are always happy to clean up their mess.
The finished rainbow should look something like this: