Enforcement of Students Playing within age-groups

Should junior students be able to play up a grade or should they play in their age group allowing the seniors their chance at the top teams as the juniors will have their opportunity in year 11 onwards?
This discussion has begun on the forum and feedback from schools about their schools policies/ guidelines on the topic would be beneficial.

Please log on to the sport coordinators section of the website, click on forum and general to find this discussion.