Fig. 3

Five-level likert scores of students’ attitudes in Exp (n = 55) and Con (n = 54) groups. Exp: experimental group with the combined BOPPPS and CBL method. Con: control group with the traditional LBL method. A self-learning enthusiasm; B study load; C systematization of teaching content; D understanding of teaching content; E student-teacher interaction; F satisfaction of teaching mode; G satisfaction of teaching effect; H self-confidence; I interest in continuing to learn about ECGs. NS: no significant difference, *p < 0.05 Exp vs. Con, **p < 0.01 Exp vs. Con