I agree that no child learns the same way ever no matter what subject area or grade level it is. According to Gardener theories of multiple intelligences’ every learner has different ways that they interact with the material and you will see this when you get your own classroom and spend day after day learning about your students and seeing their interests. Modifications and differentiation are key in all subject areas especially in small group rotations. Also grouping the small groups by levels helps them feel at ease and gives them the comfort to participate. As you had said do set higher but achievable goals for them. Also hold them accountable and share feedback. The learning pyramid explains that a student does not fully grasp the concept until he can share/ teach it to a another student.