Evening all. Did my 2nd presentation, for my DD's class, on healthy diet. Started off asking the class to put their hands up if they could tell me what a diet was. Every one of the children (apart from my DD) agreed that it was something you go on to lose weight 
, so I assumed most of them have been around . I informed them that a diet was simply a range of foods eaten by each person, and that each person's diet could be the same/similar or different from their own.
So I asked questions about different aspects of eating and emphasised that a little of everything is good, but also that too much of any food is not so good. For their age, they did very well when I asked them to do some group work and name nay healthy foods begining with P, then C.
The teacher asked about portion sizes for children of their age, so I though for a bit and remembered that a way to measure portion sizes for fruit and veg, would be for each child to have a portion size of their own cupped hand. The good thing about it is that each individual hand will grow as the child grows, so they get enough food, but not enough to feel starving IYSWIM. I read up and tested that myself, and I found that it does actually work where I feel pleasantly full, but not starving or absolutely stuffed.
If the child isn't willing to partake in the measuring, then you can use a tablespoon or, for a child under 5, a dessert/soup spoon will do just as well.