I handed out the Internal Assessment (IA) criteria for Design, along with the guidelines from the IB, and had the students analyze and discuss it. They were to identify what constitutes a “complete” score for Aspects 1, 2, and 3. Then, they assessed sample work that had been submitted by students during this past May exam period. They combed through the IAs seeking to understand the research question, the variables, and whether it was a properly controlled experiment.
I gave them explicit instructions as to how I expect the research question formulated and the variables (with units) outlined in table format. Additionally, in the table they are to discuss clearly how they will control their controlled variables. The students compared the expectations with the sample work before them and correctly identified weaknesses as well as strengths.
Next they were to design, set up and carry out an experiment of their own (Investigate a factor affecting osmosis in gummy bears). I chose something really simple this time so that they could focus on the design and their manipulative skills in the lab. It has taken all week for them to create a design with correctly identified variables and a plan to properly control the experiment. Today they busily did the initial preparations for the lab they will set up tomorrow. I was able to focus on ensuring proper lab techniques, teaching serial dilutions, how to make molar concentrations, and identifying and discussing solutions to common pitfalls in the lab. Each student had a turn to identify problems they were having in this initial phase and seek ideas and helps.
I liked the format of establishing a clear understanding of the success criteria and then having the students actually work on unique (but simple) experiments rather than employing the identical lab for all. The students are definitely invested. The designs are GOOD. The understanding is keen. Spending an entire week on making sure the students know the success criteria has unquestionably been worth our time.