Using a Google Doc and a little rainbow magic add on called Magic Rainbow Unicorns (silly name, super tool) you and your students can easily create rainbow text. The short video below shows you exactly how to do it and explains what add ons are, in case you are wondering.
How could a first grader use this?
Project a Google doc with some kind of text on it onto the whiteboard and have kids rainbowify sight words they recognize.
How could a third grader use this?
Have students rainbowify main ideas in a paragraph. You can project a doc or give each student their own copy of a doc through Classroom or through Make a Copy
How could a fifth grader use this?
Students can rainbowify opinion statements and leave fact statements black.
How could you use rainbow text to engage your students?