The paper brings the results of research into affective barriers lying at the base of negative attitudes of mathematics and language teachers towards new educational trends, i.e. the teaching of mathematics in the English language in monolingual Czech secondary school classrooms. To find blocks to the use of new approaches the method of unfinished sentences was used. The results helped to improve the curricula of the joint degree teacher training courses at Charles University in Prague, Faculty of Education. (Contains 2 footnotes.) [For complete proceedings, see ED500858.]