João Costa criticized the educational policies of former Education Minister Nuno Crato to justify the results of Portuguese year four students at TIMMS - Trends in International Mathematics and Science Study.

Timms release shows that these students have worsened their mathematics performance, having dropped from 541 points in the 2015 tests to 525 points (on a scale of 1 to 1000). According to Luís Pereira dos Santos, president of the Institute of Educational Evaluation (IAVE), this descent into Mathematics is "statistically significant". According to the Secretary of State, there were changes made by Nuno Crato's team that generated "greater learning difficulties".

João Costa assured that mathematics is "the discipline with the greatest public investment", but the result of the measures has not had much impact on the academic success of students. Therefore, he said, it is necessary to "look at the program as a whole", stressing that there are problems that are already identified, such as "the transition from the 2009 programs to curriculum goals". "There was a great anticipation of content in the goals, some of the items that were taught in the year five passed to year three, for example", he said, stressing that this change made during the mandate of Nuno Crato "generated greater learning difficulties". In addition, he added, "curriculum goals also put teaching strategies very focused on formalism, in a more abstract interpretation than what enhances better learning, which is to make this balance between content, what one learns, and the application of that knowledge."

On the other hand, the responsible refused any relationship between the worst performance of these students and the end of the national exams of year four – a measure of the current minister, Tiago Brandão Rodrigues. Two years ago, the Secretary of State created the Mathematical Working Group, coordinated by Jaime Carvalho da Silva, with the mission of developing a set of recommendations on teaching, learning and evaluation in the discipline of Mathematics. Speaking to journalists, João Costa admitted that the changes would be soon, but that first the document prepared by the GTM must be the subject of public discussion. "I will not commit to any time limit for it to come into action, because I want it to be the subject of public discussion and we may have more profound interventions on the proposal or less profound. But as we have been doing, this intervention will always be the subject of a gradual entry into force", he concluded.

According to TIMMS, year fours worsened in the three areas under analysis of mathematics. In a comparison between their abilities to "Know", "Apply" and "Reason", it is noted that the students worsened in the three areas, and the one where they got worse was in the dimension of "Knowing".