There is often debate as to whether this should be written or verbal. The age of the learner and their ability to read written feedback certainly impacts this decision. The quality of the feedback is important and I reflect on this considering the work of Dweck et al when working with students. Praising effort and hard work is critical whilst given the student an indication of next steps is also crucial.
Feedback is central focus of the original article. It outlines ways of giving feedback and the writer shares their school's policy. Links to other readings related to feedback are also given. What is of interest is the graph that is also provided and the information that is linked to evidenced based interventions.
The graph from the site simply illustrates the effect of a number of interventions. It plots them on a graph considering their cost and the impact they have on student achievement. What I particularly like is that you can click on a strategy and go to a synopsis of the research that led to the placement of that strategy on the graph. For example, I had always believed that homework isn't very effective for improving student outcomes of students. When you look at the research you see that this is indeed the case and it summarises where and when homework is effective. The website where you find this information is found here.
You can visit the source used to place these interventions on the graph at the Education Endowment Foundation. It is very useful to select an intervention and then be able to connect to the research that led the author to place it on the graph. Great access to a wealth of information about solid interventions you can try in the classroom.