Modeling (24÷3)÷2 = 24÷6 in a way that makes sense to a fifth grader is tricky. Using the definition of division is too pedantic. A rectangular array of equal groups (dividing 24 into 3 equal rows, then subdividing the rows in 2), while visually appealing, does not accurately model (24÷3)÷2. Such models generate more questions than they answer. The video below is a possible solution to this modeling problem using a bar diagram model.