Conflicting results exist in the literature on whether Open Educational Resources (OER) and
Open Educational Practices (OEP) can improve learning performance. Additionally, limited
studies, in this context, have attempted to systematically measure and understand this
phenomenon. To address this research gap, this study conducts a two-level analysis based on
a systematic review of the OER and OEP literature. It first conducts a meta- analysis to
measure the effect of OER and OEP on learning performance. It then conducts a metasynthesis based on the activity theory to understand what led to this effect (measured in the
first phase). Specifically, 32 studies (N = 134905 participants) were quantitatively and qualitatively analyzed. The obtained results revealed that OER and OEP have significant negligible
effect (g = 0.10; p < 0.05), which indicates that learners are mostly consumers of knowledge
in a very traditional way. Additionally, it is found that the learning process was mainly in
formal settings in classrooms using traditional technologies like websites and learning
management systems. The findings of this study can help to enhance the effective adoption
of OER and OEP by highlighting the confounding variables that should be considered when
developing their open education initiatives.