Year 10

Facing Kate Hayler in Year 10 hockey, Amy Pond went "for the shins". Years later, Amy and her alternate future self recalled this while fighting the Handbots on Apalapucia. (TV: The Girl Who Waited)

When she was in Year 10, Yasmin Khan once snuck into Danny Biswas' house through the window. (TV: Rosa)

Behind the scenes
Yaz in Rosa was likely referring to her tenth year at school, specifically in high school. Assuming the age range of year 10's was the same as it was in the real world, Yaz would have been aged 14-15 during this time.