Cultural revelation

On Friday we hosted 40 Chinese teenagers for sandwiches and cream teas - our fifth year in a row.
The first time we played a part in the local school exchange we took the jam and cream to the tables.
By the time we'd returned with the scones the jam and cream had pretty much gone.
One teacher told me they'd added it to the sandwiches.
So I hatched a plan.
Since then I have demonstrated how to adorn the cut scone BEFORE delivering anything to the tables.
Every year there's still a surprise.
This time the group had never drunk tea with milk. Once they'd tried it they kept asking for more and more jugs and by the end of the afternoon the cups contained a splash of tea filled up with milk.
But they don't like cheese sarnies.