If I’m only allowed to pick one thing in order to improve instruction at a school, I’d start with formative assessment. Why? Every other improvement relies on it.1
Crucially, one cannot know if a change is an improvement without having a metric with which to measure that improvement. Educators need to know if something they try works, and the answer to whether it works is, “Did it improve the thing we were hoping to improve?” Knowing whether something has improved relies on measurement, which means that one needs to get good at measurement before trying anything else. Formative assessment is the easiest way for educators to enact measurement in a way that will support their teaching efforts rather than detracting from them.
Obviously, there is research about what kinds of things work or do not work, but this research is usually hard to find, hard to interpret, and hard to contextualize. It would be ideal if educators had time to pour through the research to see what will work in their school contexts, but educational research is mostly scattered, disorganized, and unusable.
Formative assessment can be immediate (which students should I pick to answer this question?), short-term (how well did students understand this lesson?), or long-range (how well are students learning this subject?). In all three cases, educators get information they can use to judge whether some improvement effort they are making makes a difference. One does have to be a bit careful with immediate and short-term formative assessment to ensure that they match the long-term assessment results, as performance is not the same as learning, but most improvements will carry through over any time-scale.
Formative assessment is generally affordable, scalable, and unobtrusive as far as changes in schools go. It doesn’t mean it’s easy! Lots of schools confuse formative assessments with the formative assessment practices but any level of following formative assessment practices is an improvement over not using formative assessment.
The greatest strength of formative assessment is that it gives educators and their students information about how learning is going, which is crucial to any other kind of change you might want to make in schools.
