Simply put, learners learn well when they are:
. able to understand clearly what they are meant to learn and what they are to do
. given feedback about the quality of their work, as it develops
. advised about possible improvements and misconceptions
. fully involved in developing ideas, deciding next steps and what elements are unclear
. involved in dialogue, lots of it

The word assessment comes from the Latin 'to sit by'. The uses of summative assessment to determine a stage of development or to gain an external qualification are clearly important. However, formative assessment has a very effective role to play in learning. Due to the highly influential work of Dylan William and Paul Black ('Inside the Black Box') there is now a clear view about using assessment to provide feedback to the learner and the teacher. In ongoing developments in schools, involving students in the construction of understanding and skills now seems an essential part rather than an add-on benefit.
. 'An assessment activity can support learning, rather than merely measuring it, if it provides information that is used as feedback, to modify the teaching and learning activities in which students and teachers are engaged.'
. 'Such assessment becomes 'formative assessment' when the evidence is actually used to adapt the teaching work to meet the students' learning needs.'
. 'This is assessment for learning rather than assessment of learning.'
Paul Black, Dylan William et al 2002

Preamble: how does assessment support learning?
To provide for learning, lesson tasks are either designed (or clutched at.) to attend to subject specific features of selected content or process (even in cross-curricular work). Assuming a task is appropriately pitched, not too steep a path and not too trivial, there will almost inevitably be an initial fogginess and wobbliness over understanding. Learning takes place over time and will be aided by opportunities to communicate with others, developing a shared understanding through interaction in a learning community that is pleasant, tolerant, appreciates tentative steps and is not too harshly critical.

Self-assessment (and emotionally laden doubt) arises naturally as a learner stumbles towards understanding and either leads to individual engagement or giving up. Feedback and encouragement can offer the learner a necessary 'scaffolding' that helps grappling, in mental construction work. Formal feedback through marking and testing also helps, particularly through setting standards, but lacks the immediacy that is often required in the learning process. The teacher plays a lively and sophisticated role in provoking thought, picking up on student ideas, addressing misconceptions and valuing contributions and student questions.

The classroom should not be a place where students observe a teacher at work. Ideas are best developed with students rather than for them, rooting learning in the reality of classroom antics rather than curriculum coverage. Assessment then is a natural and significant part of learning and making mistakes is to be encouraged! Assessment for learning builds more substantially upon this, to provoke routine procedures that normally encourage understanding and move learning onwards and upwards.

The main practices of assessment for learning involve:
. Identifying clear objectives for lessons and communicating these to students: what they are trying to learn (learning objectives), what 'good' looks like (success criteria) and why they are learning this (overview considerations);
. Conveying an understanding of subject progression, e.g. what to work on in order to improve;
. Using teacher questioning and dialogue to probe understanding and ascertain misconceptions, learning from each other;
. Providing effective feedback through marking and oral interchanges, with opportunities to respond to feedback and ask their own questions built in to lessons;
. Involving students in peer- and self-assessment (through a knowledge of criteria), assessing their own level of understanding and recognising how to improve it;
. The formative use of summative tests (and other assessments).

(AfL) Questioning (see also the 'questioning' section)
. Creating a climate where pupils feel safe to make mistakes - so that all pupils have the opportunity to answer questions and it isn't just left to a dominant, vocal, few. Pupils should feel comfortable to offer tentative thoughts without fear of ridicule.
. Using a 'no-hands rule' - or otherwise ensuring that all students, especially the shyest, have an opportunity to contribute in lessons. Some teachers choose to direct a question to a girl then a boy, alternately.
. Probing - to check meaning; displaying an interest in student answers; praising and encouraging elaboration (i.e. to 'edit or amplify').
. Telling pupils the big question in advance - so that they have an overview and are able to identify the main purpose of the lesson, how it relates to previous work and other, bigger, ideas.
. Building in wait time - critical in allowing students to develop and then articulate their ideas. Research shows clearly that student answers improve considerably when a wait time of 3 to 4 seconds is allowed.
. Allowing paired discussion for a while - leading to more thoughtful and considered answers. It can also help to promote engagement.
. Encouraging lengthier student responses - maybe by remaining silent after a student has answered; possibly asking them to say more; possibly by asking for them to give reasons as well as ideas ("I think .. because..")

(AfL) Providing feedback through marking of work (some tactics)
. Marking is an analysis of students' work to determine learning needs. It is a necessary chore that needs to be minimised so that there is time for lesson preparation.
. Marking seeks action.
. Grades or marks out of 10 for homework divert attention and emphasise competition rather than personal improvement.
. Grades for longer pieces of work can help a student know 'where they are at'.
. Specific comments, on aspects of work, advise a student how to progress. It is done for students rather than to them.
. Good feedback prompts student thought. It leaves work for the student to do. It may provide an impetus for the student to discuss their work, with a teacher or another student. It might expect a response. Errors can be indicated rather than corrected.
. Ask a student to go through a homework question on the board at the start of a lesson, maybe with help and advice from other students.
. Students can self-mark or peer-mark work when provided with clear criteria.
. Ask students to read and reflect on your comments at the start of a lesson and ask them to be clear about and maybe write a note about how they could improve/correct their work.
. Give time for students to discuss the teacher's feedback with another student. Comments are a waste of time unless time is set aside for students to consider and act upon them.
. There's a positive side to 'negative marking'. Flaws (patterns of errors) need to be identified. Mistakes are very helpful to the learning process.
. Electronically scan a student's work and project it, to provide a larger audience for their work. Invite students to comment on solutions ("what advice would you give?")
. Consider what a really good response to a tough question might look like.
. Marking praises and rewards a very good effort and communicates interest.
. There are opportunities for looking back over previous lessons and revisiting topics, however briefly.
. Lesson tasks are adjusted in the light of poor or very good responses to a homework task.
. Tasks value creativity and imagination and this is positively supported wherever it occurs.

(AfL) Involving students in self- and peer-assessment
. These forms of student driven assessment, and the accompanying discussions, help to establish a classroom culture of constructive reflection. They are particularly helpful for assessment of more complex aspects, e.g. those for coursework or process targets.
. It's unrealistic for a teacher to be able to assess all the work that students do. Self-and peer-assessment play a helpful role in more thoroughly checking student work.
. It is helpful for students to understand learning goals so that they can gauge their own progress, becoming more involved in appreciating their progress and believing that their attainment can improve.
. Peer assessment is one of the main vehicles to promoting effective self-assessment. Seeing how other students tackle a task can be highly informative.
. Peer work is particularly valuable because the dialogue can be in a language that fellow students may more naturally use and more readily understand.
. Students learn most by trying to teach or explain an idea, e.g. on the board.
. Students need to understand the criteria of quality and develop an overview of a topic. Modelling exercises can be helpful, sometimes using students' work (e.g. from a previous year, presented anonymously). Criteria need to be written in a student-friendly form.
. When students collaborate there are much greater learning gains. Some training is necessary for this to be maximally effective.
. NC level statements are sometimes too coarse to help learning progress. Exam marking schemes and examiner's reports can be made available.
. Students can take criticism from a peer more seriously than they would from a teacher. A student could lead a plenary review, with additional points made by others.
. Feedback from a class to a teacher can be strengthened by peer collaboration. Concerns and misconceptions can be raised and tackled.
. Several teachers ask students to use 'traffic lights' (in their work) or facial gestures (in class, e.g. thumbs up) to indicate a good, partial or poor understanding. Sometimes elected colours can be grouped together, e.g. for extension or intervention work.
. The process of enabling students to be more independent in the way they evaluate their own work takes time and training - but is effective in the long run.
. 'Two stars and a wish' - a simple device for asking students to comment on a piece of work by suggesting two things done well and one area for improvement.
. It provides time for a teacher to work with individuals or to frame an intervention.
. Over time, students can build awareness, across subjects, of metacognitive skills and a hierarchy of cognitive skills (e.g. as provided in Bloom's taxonomy).

(AfL) The formative use of summative tests (and other assessments)
. Testing and other more formal assessments have an important feedback role - to the teacher and students. They set standards, provide information on what learning has been effective and can be a positive part of the learning process, motivational for many students.
. When attainment in summative assessments becomes or appears to be the main goal of education the effect can be to raise the status of short term instrumental gains rather than developing longer term, relational understanding.
. Formative assessment needs to work alongside summative assessment. Formative strategies can assist preparation for summative assessment.
. The effective review/revision of work in preparation for a test and the aftermath/unpicking of tests are important elements of looking back over work, develops confidence and identifies problem areas - a formative assessment culture.
. Students can be given a short test around two thirds of the way through (i.e. an interim assessment), rather than always at the end of a series of lessons to identify and deal with difficulties. In general it seems preferable to have shorter and more frequent assessments that can impact on learning rather than merely evaluating it (when it's too late).
. Students can be given the mark scheme for a test (especially for external assessments) and asked to identify their particular problem areas (e.g. three errors). They can be encouraged to understand why their answer was wrong and see that attainment is trainable.
. A teacher can focus on specific questions that caused most problems and leave the smaller gaps to be discussed with a neighbour or someone in the class who had answered correctly. Further examples of wider troublesome areas can be provided. This helps students to focus on understanding their errors rather than looking where they should have been given extra marks.
. Students can work in groups on questions, maybe after they have taken the test individually. They can also be asked to write questions for a class test, with a mark scheme. Preparing test questions involves students in reviewing and forming an overview of a topic.
. Following a test, a teacher can provide students with examples of many of the errors made within the test and ask students to correct them.
. Revision and reviewing strategies need to be taught.
. Students can be helped/trained to become 'experts' on individual exam questions.
. Good solutions can be shown on the board as a model, maybe anonymously.
. It is helpful to have many past paper questions available electronically (with mark schemes) so that students can choose their own questions to study.

The 'Association for Achievement and Improvement through Assessment' website very helpfully collects together a full range of resources:
http://www.aaia.org.uk

The Scottish, Learning and Teaching has a similarly extensive range of helpful material:
http://www.ltscotland.org.uk/assess/for/intro.asp

QCA's guidance on AfL:
http://www.qca.org.uk/qca_4334.aspx

Working inside the black box
'Working Inside the Black Box' (2002) develops ideas from 'Inside the Black Box'. To embed assessment for learning, to realise the benefits, main findings from the work in schools are grouped under four headings.

Questioning
. More effort has to be spent in framing questions that are worth asking.
. Wait time has to be increased to several seconds to give pupils time to think and everyone should be expected to contribute to the discussion.
. Follow-up activities have to provide opportunities to ensure that meaningful interventions that extend pupils' understanding take place.
The only point of asking questions is to raise issues about which the teacher needs information or about which the pupils need to think.

Feedback through marking
. Written tasks, alongside oral questioning, should encourage pupils to develop and show understanding of the key features of what they have learned.
. Comments should identify what has been done well and what still needs improvement, and give guidance on how to make that improvement.
. Opportunities for pupils to follow up comments should be planned as part of the overall learning process.
To be effective, feedback should cause thinking to take place.

Peer and self assessment
. The criteria for evaluating any learning achievements must be transparent to pupils to enable them to have a clear overview both of the aims of their work and what it means to complete it successfully.
. Pupils should be taught the habits and skills of collaboration in peer assessment.
. Pupils should be encouraged to keep in mind the aims of their work and to assess their own progress to meet these aims as they proceed.

Peer and self assessment make unique contributions to the development of pupils' learning - they secure aims that cannot be achieved in any other way.

The formative use of summative tests
. Pupils should be engaged in a reflective review of the work they have done to enable them to plan their revision effectively.
. Pupils should be encouraged to set questions and mark answers to help them, both to understand the assessment process and to focus further efforts for improvement.
. Pupils should be encouraged through peer and self assessment to apply criteria to help them understand how their work might be improved.

Summative tests should be, and should be seen to be, a positive part of the learning process.

The underlying issues identified are:
. learning theory - teachers need to know in advance what sort of feedback will be useful, i.e. they need to understand how their pupils learn;
. subject differences - teachers need to have an understanding of the fundamental principles of the subject, an understanding of the kinds of difficulties that pupils might have and the creativity to think up questions which can stimulate productive thinking; such pedagogical content knowledge is essential in interpreting response;
. motivation and self-esteem - learning is not just a cognitive exercise, it involves the whole person; learning for learning rather than for rewards or grades;
. a learning environment: principles and plans - teachers need to have forethought of how to teach in a way which establishes a supportive climate;
. a learning environment: roles and responsibilities - teachers need to help pupils become active learners who can take increasing responsibility for their progress.

Watch a recent talk by Dylan Wiliam (September 2007) where he explains the emerging powers of technology to considerably enhance assessment practice:
http://www.alt.ac.uk/altc2007/

Assessment for Learning - 10 Principles
DfES - Unit 12 Assessment for Learning
Inside the Black Box