As schools begin reopening around the world, education systems are faced with the challenge of mitigating learning lost during the pandemic, designing and implementing remedial or accelerated learning programmes, remote learning and next year's curriculum. Effective teachers are a crucial part of supporting learning recovery. School closure during COVID-19 has left many teachers uncertain about their role, worried about their working conditions and their health, safety and wellbeing, unable to use technology effectively, and unprepared for classroom challenges when schools reopen. Teachers will need to respond to students' academic losses (and gains), but also to their socio-emotional wellbeing. United Nations Educational, Scientific and Cultural Organisation (UNESCO) and Education Development Trust have undertaken this study to provide information to help teachers, schools and governments understand how to support teachers to best support students as they return to school. This research is designed to allow to focus on the available existing evidence, and focuses on the most marginalised students and include research from previous crisis and disaster contexts to examine broadly what is know about actions to mitigate and recover learning loss, not just related to the current global pandemic but in a broader sense. The key research questions for this Rapid Evidence Assessment (REA) are grouped into two sections. Firstly, questions about learning loss, gain and impact on student wellbeing. The second group of questions focus on the experience of teachers and the literature around the skills and support required for teachers to recover learning and wellbeing themselves and in students as they return to school. The REA is a companion to a review of policy and grey literature which focuses more on commentary and guidance literature. These papers are the first stage in a wider research project which will look at how teachers support learning recovery post COVID-19. [For "Learning Loss, Learning Gains and Wellbeing: A Review of Policy and Grey Literature," see ED615067.]