The COVID-19 pandemic forced many countries to impose a strict lockdown policy on citizens during a prolonged period of time, which led to changes in lifestyle habits. This unprecedented situation has given rise to numerous studies aimed at determining the effects of the changes brought about by this widespread lockdown. One of the important changes was the digitisation of education and, therefore, teaching, which caused a forced and abrupt immersion in distance learning. In this study, a quantitative methodology based on an ex post facto research design was used with the aim of analysing the impact of the COVID-19 lockdown on the academic performance of schoolchildren (aged 3-12 years). A total of 529 parents completed an ad hoc questionnaire on the impact of COVID-19 on their children's education in Spain. The results produced a robust model based on structural equations that explain 39.7% of the variance in academic performance at home. The family-school relationship was the variable with the greatest explanatory weight ([beta]=0.505; p<0.05). In conclusion, the benefits derived from a strong relationship between families and schools, evidenced by the creation of cooperation and communication links, facilitate the management of shared educational challenges such as on-line education in times of crises.