In assessment, we need to understand 3 issues. 1. Assessment of learning 2. Assessment for learning 3. Assessment as learning. 

Assessment of learning: This is a type of assessment through which we can estimate, measure, calculate the achievement of Learning Outcomes or reaching the Academic Standards targeted. This has to be conducted after providing learning experience. The periodical tests like unit tests, terminal examinations are examples. Assessment of learning is used to analyse the quality as well as the quantity of learning takes place. Assessment of learning usually takes place after completing a unit or over a period of time....which is planned, announced.....

Assessment for learning is the assessment that is done to check whether the learning has been done as it should be done. It is done during the classroom transaction....while the children are involved in the learning tasks...so that the result is useful to provide feedback to the teacher so as to enable him/her to make necessary changes in the learning material, experiences, teaching techniques etc. Simple unannounced class test, or any quiz, or children's responses, works done in the notebooks can be considered as examples.

Assessment as learning is nothing but using assessment as a learning strategy.....like other strategies like discussions, interactions etc.