Thomson defines educational science, which he sees as having two facets: operational, such as the research undertaken by the Scottish Council for Research in Education regarding the best teaching methods; and fundamental, such as research undertaken to explore the sources of intelligence differences, and their relationship to one another.

Thomson charts how educational science has progressed, due in part to the use of mathematical statistics and the increasing use of quantitative measurements. He cites the application of statistical tests to the results of educational experiments to determine their significance as an example.

Thomson looks closely at the issue of nature versus nurture, making particular reference to the Scottish Mental Surveys, and studies carried out on siblings and twins. He talks about both the usefulness and limitations of intelligence testing, and the possibilities of factor analysis in identifying the different abilities within an individual's mind. He describes some issues he thinks are worthy of investigation by educational science, including the notion of transfer beyond school, selection for secondary school and further education, techniques for memorising in the classroom, and propaganda in the classroom.