We have placed children in classes based on their year group and friendship groups. We have also tried to match students to teachers with whom we believe they will thrive.
Composite classes will not alter how we teach, all of our students will be taught whatever they individually need to know next, just as they are now. For example, we can have three students who are all in Year 4 but with very different skills. Currently one might be learning something from the Year 4 curriculum but another student might be learning something from the Year 5 curriculum and the third student might be learning something from the Year 3 curriculum.
Our teachers have the capacity to manage to teach all three levels simultaneously and this will continue to happen. In that sense, the nominal age (year level) of a student does not matter.