In Catholic tradition, popes write encyclicals (letters) to address concerns of the day. These are based on scripture and become part of magisterium teachings which Catholics use to inform their conscience. RE teachers can of course use these as ‘religious teachings’. This encyclical is often cited as the first example of CST in which the Pope addresses the conditions of labour, workers' rights, and social justice, written in the rapidly changing industrial society of the late-19th century. Pope Leo emphasises the inherent dignity of every individual as a creation of God, condemns the exploitation of workers and asserts that both employers and workers have a duty to recognise and respect each other's humanity. He goes on to discuss the role of the state, promotes the idea of solidarity, introduces the principle of subsidiarity, which suggests that social and economic issues should be addressed at the most local level possible, allowing individuals and communities to take charge of their own affairs. He also calls on the Catholic Church to play a role in addressing social issues and advocating for the rights and dignity of workers. RE teachers could plan to use this after their students have studied the Industrial Revolution in History, so that they have the prior knowledge to promote deeper engagement. Teachers could give students a short extract (for example paragraph 20) and challenge them to pick out CST themes and what this could mean for Catholics today in how they live their lives (for example in relation to fair pay and conditions). Many of the topics with the GCSE theme human rights and social justice can be found within this encyclical.