Hi Holly, I have not come across anything specific to ACEs or Trauma in terms of class size. You could look at studies on class size reduction and make connections between the benefits observed and what we know about setting the right conditions for learning to support students that have been exposed to trauma. For example if class size reduction is shown to benefit engagement and relationships, these 2 strategies have also been shown to be factors that have a positive impact on all students- especially those that have experienced trauma. Just my 2 cents.