The archive footage contained a clip of Treorchy Comprehensive School. BBC Wales' cataloguing data revealed that it dated from when the school opened in 1965.
Valleys Kids had strong connections with Penyrenglyn Community Primary School, most of whose pupils go up to the comprehensive when they leave Year 6.
So the primary school staff invited some teachers who used to work at the comprehensive to come and see the clip.
It was an amazing moment when we found that the teachers in the room with us were some of the only adults to appear in the old footage.
They told their stories to the Year 6s who thought about them and responded with a story of their own.