Foundational knowledge in primary school covers essential skills like literacy (reading, writing, vocabulary), numeracy (basic math), and key concepts that build a base for future learning, alongside crucial social-emotional skills (focus, self-regulation) and general world knowledge, ensuring children can understand, communicate, and progress across the curriculum, especially by the end of Key Stage 1. It's about mastering fundamental facts and cognitive abilities (like remembering and understanding) that enable more complex learning later on.