Thanks for asking epainter! That's a brave question. I don't have time to go on and on (fortunately) but here's one and I'll let others chime in.
Give open-ended assignments. For example, if it's volcanoes, be sure that finishing the assignment isn't the ceiling. If they are researching or creating something then some kids will do more (and the kids who do less shouldn't be penalized). Example, my 4th grade son always wrote a 5 paragraph essay when the teacher said to write a five paragraph essay. When he was give a creative writing assignment in 5th grade with no rules, he wrote a book (literally).
