Economics of education is a very interesting field for any economist, especially for young student economists. When considering the determinants of the educational production function, there are several factors that naively would strike us, economy students, as essential features of learning, no questions asked.
In view of empirical results in what concerns resources, I was shocked to realize that student/teacher ratio, the availability of books and blackboards did not seem to have a significant impact on learning. But is this a “true” result, or one that arises from informational problems in what concerns data?
This comment has the objective to shed light solely on one factor above mentioned: blackboards. Well, every school that any person that may be reading this attended, probably had a blackboard, (or any other type of board). Although, in the master the blackboard is falling underused, while slide projection is dominating my classes, I fail to understand how a blackboard is not a crucial element in effective learning. Actually when a demonstration is shown on a slide my understanding of it is quite insignificant when considering the understanding when the same demonstration is derived on the board by the same teacher. If this happens in higher education, how will primary school student learn simple summation or fractions without seeing it done in front of them?
Looking further on this subject we can realize that in the same paper, while Blackboards are not significant, teacher attendance is. Well, if a teacher is not present, then a blackboard will be obsolete. This can clearly influence the outcome of this variable. If we consider that in all schools of all developed countries every classroom have a board, then this variable is only of relevance for developing countries, which is a reasonable assumption. Well in this scenario it is more likely that a teacher is not attending school regularly, and also that there is no correlation between the existence of a blackboard and teacher attendance. Given this, and the fact that a board will not teach by itself, it is likely that this variable is not properly studied.
Moreover, we can also think about another important thing. In such countries, infrastructure investment may exist without being backed up by maintenance investment. So, it is likely that blackboards exist but chalk doesn’t– this will go against all the usefulness of a blackboard and bias the results for this variable – its existence will not be of any use for learning if there is no teacher, neither it will be without chalk.
Given this what could be an alternative to study this variable? Well if we consider the joint existence of blackboard and chalk it will eliminate part of the bias. Also it is likely that a school have periods with chalk and periods without – so a proportion of time could be used. As this data would be hard to collect, we could compute this using a proxy, such as a number of classes and chalk orders relation, (given the fact that it is likely that there are not many manufacturers, and we need to have information on how much chalk is being used).
Furthermore this could also be pondered by the percentage of time the teacher attends, and therefore only the useful time of the board would be accounted for, eliminating the biggest threats for empirical research on this variable.
Maria Martins #540
 According to Glewwe ET AL, 2011, NBER working-paper nº17554