The aim of this work was to readjust the practical classes carried out in the first year of secondary school at a school, with a view to cost-effectiveness in terms of reducing the cost of reagents, but above all to reducing the waste generated in these practical classes. In the case of an educational institution, it should focus on making its students aware of the environmental impacts caused by excessive waste, guided by the concepts of Green Chemistry and Environmental Chemistry and sustainability, with a view to reducing the time, energy and materials needed to treat waste.