It may be that newly published materials are 'on trial' in one or more classes with a view to deciding whether or not to adopt them as part of the school programme. It may be that new materials are in the process of being developed or adapted, either within the school or by others and 'field trials' are in progress in order to amend and improve the drafts. In all cases, except perhaps books meant only for private reading by pupils, it is likely that a teacher will not want to judge only from what he or she can see on paper, film or computer screen. It will be important to use the materials with pupils and to take into account pupils' actions and reactions. Curriculum materials are devised to help pupils learn.
Evaluation has an important part to play in decisions about classroom materials.
This approach to curriculum materials evaluation seems so logical that the reasons for not suggesting it ought to be pointed out before we look at the alternatives. Indeed it was the approach advocated, particularly in the United States, for evaluating new materials which were produced in the heyday of large-scale curriculum development in the 1950s and 1960s. However, when it was seriously tried in practice it was found to be fundamentally flawed. The objections which apply to large-scale evaluations of materials apply even more clearly to those on a smaller scale. They are both practical and theoretical.