Probing student understanding & pre-conceptions that influence their new learning: the 2-tier MC

It is well documented that new learning is greatly influenced by prior conceptions and learning (constructivist theory). Multiple choice testing, though a powerful and efficient and very standard way of measuring student achievement and understanding, in both universities and high school, such as the IB Diploma Programme for instance, where the entire Paper 1 in chemistry is multiple choice, has been criticized as not telling the instructor about the reasoning and justification behind the student's reasoning. A great way to get around this is to design two-tier multiple-choice assessments where in part 1, students select the correct option, but in part 2 of the the question, they have to circle the correct justification for their answer in part 1. Although I learned about this versatile method in the Senior Chemistry Instruction Course 2 years ago, I have not actually implemented using this in my classrooms. This is a goal early this term.