During initial discussions about what fraction division problems are asking, presenting problems with common denominator can easily highlight important mathematical ideas.
For example, see part A of the Hamburger problem: Solving this division situation involves finding how many groups of three 1/10 size units are in nine 1/10 size units.
This problem parallels reasoning that students have used with the whole-number division problem 9 ÷ 3 = 3 when finding how many groups of three are in nine.
Figure 3 highlights models that students developed when solving part A of the Hamburger problem.