Feedback means fixing not marking – try snowballing

Feedback means fixing – not marking

Many teachers interpret ‘feedback’ or ‘formative assessment’ to mean commenting on students work, and annotating it with ticks, crosses, and comments and so on. Some think this includes grades or marks.

But the guru on formative assessment and feedback, Dylan Wiliam, interprets the terms differently. For him the purpose of feedback is not just to comment on progress to date, but to fix the errors and omissions in students’ understanding, and to help students identify exactly what a good piece of work looks like.

Dylan points out that feedback is an engineer’s term. A thermostat tells your boiler that the temperature is 5° too low (this is like a comment or a grade) then this information turns the boiler on (this is the fix). Without the fix, there is no benefit from the feedback.

A misconception teachers often have is that it is they who must provide feedback and formative assessment. But students can do a pretty good job for themselves and each other, saving you some trouble, as well as teaching students about how to assess, and the nature of good work.

Done well, feedback can have a huge impact on students’ learning. Let’s look at an example of good practice: the Snowball teaching method.



One use of snowball is to get students to evaluate an imperfect piece of work. I will imagine you have just explained to your students how to use commas. But this approach could be used to teach them how to write a good marketing plan, care plan, or experimental design. You could also use this approach to teach students how to rearrange algebraic expressions, indeed pretty much any intellectual skill.

Having explained how to use commas you will want to give them feedback on their understanding before they start to use the skill. You give them a few paragraphs of punctuated text, but it contains errors and omissions in the use of commas. Students are then told the following sequence in advance, and challenged to find all the errors and omissions in the example given them, and to be able to explain these.

  1. Students work alone to detect the faults in the text.
  2. Students pair up to discuss the improper use of commas that they have found, and to combine and improve their ideas.
  3. Pairs combine into fours, and again ideas are discussed and improved. Together they create the best, reasoned critique of the punctuation they can.
  4. Now you get one idea from each group of four in turn. You choose a member of the group to give one problem with the punctuation, and perhaps another to explain why this is a problem and what the solution is. You don’t comment on their thinking at this stage except to clarify it.
  5. For each point made by a group you ask the class if they agree or not, and why. There is class discussion. You record the class’s conclusions on the board, whether these are right or wrong, and without evaluating them.
  6. You repeat 4 and 5 above with the other groups, until all the comments on the use of commas have been collected.
  7. You now comment on the class’s thinking for the first time, and correct errors and omissions in this.


Why does this teaching method work so well? When people learn they make links between neurons (brain cells). The new learning (red in the diagram below), is connected to prior learning (black in the diagram). This new learning encodes the student’s version of what you have explained. It is called the student’s ‘construct’ for how to use commas.

High quality learning diagThis construct will have errors and omissions in it, because it was not made by you, but by the student. If you are not convinced, at the end of one of your lessons, ask your students to write down what they have just learned on a piece of paper. Collect these in – and read them. You will be astounded at how your perfect explanations have been garbled and corrupted! And of the vital need for formative assessment.

The best way to fix these errors and omissions is to engage the learners in active learning on a challenging task with feedback. This requires the student to form an understanding, then checks and corrects this understanding, and so improves it. Snowball does this pretty well, as each student will go round the quality learning cycle a number of times: probably when working alone, certainly in pairs when there is a disagreement, again in fours, and yet again during class discussion. The construct is improved at each stage.

You also get excellent feedback on their understanding. This enables you to re-teach the points which students have not understood.

There are no written comments or grades during Snowball, but there is plenty of feedback …. Vitally, this goes on to produce plenty of fixing! The feedback in Snowballing has not just corrected students’ work, it has corrected their understanding. And your teaching!

Snowballing will not be enough by itself to teach the use of commas, students will now need individual practice at punctuating text, or creating marketing plans etc. But they will find this practice very much easier if they have snowballed first, and less practice will be needed to establish the skill. This practice could be snowballed as well, or instead. Snowball has lots of uses!

So feedback or formative assessment does not require the teacher to do all the work, or to provide lots of comments and marks. Its main aim is to get students to understand what they are trying to do, what they do well, and what they don’t, and to fix misunderstandings.

Some common misunderstandings regarding feedback

Feedback has most effect when it creates ‘cognitive conflict’ meaning that that student is puzzled they got it wrong, and starts to work out why, Hattie (2003). Disagreements during the snowball discussions create these cognitive conflicts, which are usually resolved by the students, or later by the teacher. So snowballing, used well, can have more effect than you marking student work.  You will of course need to mark student work sometimes in order to get feedback on their performance, but feedback to students is often best done through discussion.


Hattie, J. (2003) Why is it so difficult to enhance self-concept in the classroom: the power of feedback in the self-concept – achievement relationship. Conference paper available free on-line by searching for the title.












5 thoughts on “Feedback means fixing not marking – try snowballing

  1. Snowballing is a very active learning and teaching style. It supports collaborative working and improved communication skills too. Students are given ownership for their learning and most of all self assessment, leading to identifying their own personal learning targets, which they should be encouraged to set each session themselves if not totally develpoed by themselves. They must be able to be self crtics which improves their relationship to receiving feedback in a more constructive manner.

    • I agree with the thrust of your comment and thanks for it! I don’t think students need necessarily set formal targets for improvement as a part of snowballing necessarily. A lot of learning during snowball just comes from students learning informally from each other, they hear ideas they had not thought of themselves, and they have to think hard about the topic they are learning during discussion if the task is well designed and if teacher manages behaviour etc well.

  2. Hello,I read your blog named “Feedback means fixing not marking – try snowballing – Geoff PettyGeoff Petty” regularly.Your humoristic style is awesome, keep up the good work! And you can look our website about proxy list.

  3. Hello,
    I work with changing, long term/short term mixed cohorts of students, who are in hospital with mental health issues. Many have diagnosis of ASC and Asperger’s, Dyslexia, Dyspraxia and communication difficulties (and associated eating disorders). Assessing their work can be triggering for those who have complex issues and anxieties around pressures of doing well/not well, so I try to leave out grades during feedback (I do however document their grades for data). Students sometimes find it difficult to peer/self assess but I think this method of snowballing might be a way forward and help with differentiation while being totally inclusive. For some students a target may simply be ‘staying in a lesson for short period of time’ or ‘engaging in activities/tasks’ that they might previously have been to unwell to do so.
    My lessons are Art and PSHE, groups are small so discussion and debate are often done in written form for those who are too self conscious to discuss verbally, occasionally pairing is effective. I would appreciate any tips and advice about formative assessment and snowballing in small group situations for learners with the above difficulties. Thank you.

    • Hi Lizzie, I can see you have a very challenging teaching situation. I’ve never taught in your context so I am wary of giving advice, also, most of the research on feedback is in more conventional contexts. However, there is little doubt that most feedback methods can be adapted for your students. I would try ‘spoof assessment’ or ‘anonymised assessment’ with your students, where you give students work done by ‘a student last year’ though you may have made it up. When students assess this there are not egos at stake. You can use this to develop ideas in your subjects, and to prepare students for a new art project by looking at what other students have done in response to similar projects.
      Targets must be tailored to the student, so ‘staying in the lesson’ might well be appropriate.
      You might find the following book useful: Westwood, P. “Common Sense Methods for Children with Special Educational Needs: Strategies for the Regular Classroom”

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