That mathematics was the path he eventually chose was largely due to the influence of two of his teachers, Mr Schindler and Mr Seebeck, who succeeded in further arousing his interest in and enthusiasm for the subject. Stäckel's reference, written at the end of his schooling in 1880, talks of:
Na matematika ay ang landas siya sa huli ay pinili sa kalakhan dahil sa impluwensiya ng dalawang ng kanyang mga guro, Mr Schindler at Mr Seebeck, na Tagumpay sa karagdagang arousing kanyang interes sa at sigasig para sa paksa. Stäckel's reference, nakasulat sa dulo ng kanyang-aaral sa 1880, makikipag-usap ng: