The COVID Social Mobility & Opportunities (COSMO) study is a new national cohort study generating high-quality evidence about how the COVID-19 pandemic has affected socio-economic inequalities in life chances, both in terms of short- and long-term effects on education, wellbeing, and career outcomes. A representative sample of young people in England who were in Year 11 in the 2021/2022 academic year were invited to take part in the survey, with the aim of following them as they progress through the final stages of education and into the labour market. This first brief finds that there were substantial gaps between state and private secondary schools in the intensity of remote learning during the first lockdown in 2020, with the private sector much better placed to adapt quickly. Barriers to remote learning were all more likely to be experienced by young people from lower socio-economic backgrounds, and those who experienced those barriers reported working fewer hours during lockdowns. Patterns by ethnicity and race were mixed. [For the second brief, "Education Recovery and Catch Up," see ED625714. For the third brief, "Future Plans and Aspirations," see ED625715. For the fourth brief, "Mental Health and Wellbeing," see ED625716.]