The covid-19 and the restrictions imposed by the lockdown affected educational institutions across the world and forced them to adopt a new way of teaching called emergency remoteteaching and learning.This master thesis focuses on challenges to teach mathematics remotely experienced bysecondary school teachers during this period. The data collection was conducted through semistructured interviews among secondary school mathematics teachers, active in the Covid-19lockdown. The collected data is analyzed and discussed from the theory of connectivismperspective and research findings are produced and structured based on the themes resultedfrom the literature review. The findings show that mathematics teachers encountered many challenges with the process of teaching especially due to the rapid transfer from traditionalclassroom teaching to online classes. Teachers’ knowledge and skills in using Information Communication Technology (ICT) tools are identified as main factors for a successful andeffective tuition in remote mathematics. The respondents see the opportunities in using ICT intheir teaching processes both from their perspective but also from the student perspective. The conclusions of this master thesis research show that use of ICT tools and platforms in teachingmathematics remotely is effective as extra tools and not as a complete and permanent substitutefor traditional classes. As a suggestion, remote teaching may be seen as a valuable alternativeif the actual pedagogical strategies are adapted, and ICT courses are introduced in the teacher’seducation. Yet, there are not enough studies to support this idea and the findings in this studyand more research could help to get a better understanding. The thesis offers suggestions forfurther research regarding remote mathematics teaching both from the challenges point of view but also in regard to the advantages remote teaching may imply.