Finding mistakes in my teaching

My cooperating teacher and I have been co-planning our classes together, and I take her plans and flesh them out into more formal plans for methods class. However, I'm only doing that for the Algebra and CMP2 classes, not for our Study Tech class.  So when I started teaching Study Tech today, I realized that I didn't have a detailed feeling of where our class needed to go.  Frequently, we are previewing or reviewing concepts these students will see in their CMP2 class.  We were working on equivalent fractions today, something all of the students struggle with to some degree.  I reviewed the worksheet that they had for homework by asking students how they solved the problems, and then we gave the students another worksheet to practice with positive and negative numbers.  After 5 minutes of working with the students, I saw they needed more scaffolding, so I asked them to write down each time the fraction they multiplied by to get the equivalent fraction (ie, 5/5, 3/3, 8/8, etc.) Most students kept working on the problems, but in going around to assess their progress, none of them were writing down the intermediate step.  I didn't make that step mandatory, so they weren't doing it, even though it would have helped most students understand the process. I wish I could go back and reteach this lesson, making sure that students write down the ratio they are using to find their answer.  Next time, I'll know!