Ysgol Gyfun Gymraeg Plasmawr is a close-knit community in which the school motto, ‘Parch, Parodrwydd, Perthyn’ (‘Be respectful, Be prepared, Belong’), is central to everything. The pastoral care and support the school provides for pupils is a notable strength. As a result, most pupils feel safe, are polite and are well behaved. Many develop to be mature citizens. The sixth form plays a key role in school life. Sixth form students lead clubs for younger pupils and a number of forums that support pupils to develop their understanding of tolerance, equality and fairness. A notable example of this is the ‘Newid Ffem’ group, where sixth form pupils support the school’s younger girls in a variety of ways. Overall, sixth form pupils make strong progress in their academic studies. The new headteacher has a clear vision for the school and, in a very short time, has identified the main strengths and areas for improvement. Leaders across the school provide high levels of support for staff and effective leadership in terms of provision for well-being and additional learning needs (ALN). Governors provide strong support and undertake their role as a critical friend appropriately. However, leadership of teaching and learning is not effective enough. Leaders do not evaluate the quality of teaching or provision for skills incisively enough, as they do not give enough consideration to the effect of provision on learning. As a result, they do not identify in sufficient detail the specific aspects that need to be improved in these areas. Leaders also do not hold those they lead sufficiently accountable for their work. The school provides a balanced curriculum that is enriched by the valuable partnership with other Welsh-medium secondary schools in Cardiff. The school’s work for the Curriculum for Wales is developing appropriately. It has worked suitably with parents, staff, pupils and primary schools in the cluster to create a clear vision that is based on ensuring pupil well-being, developing their values and providing learning experiences that build on previous learning. Most teachers foster positive working relationships with their classes and, in a majority of lessons, pupils make secure progress in their subject knowledge. Many pupils have positive attitudes to learning. However, in a minority of lessons, the quality of teaching is not good enough and the quality of assessment and feedback for pupils is inconsistent. Overall, pupils develop their skills appropriately. However, provision for skills is not co-ordinated well enough, particularly provision to develop pupils’ digital and numeracy skills across the curriculum. There is a strong culture of safeguarding within the school, but a few health and safety issues were brought to the attention of the school during the inspection.