How to help your child get more organised: tips from a Hong Kong teacher

It is interesting that you have given the list to the helper. Getting organised begins at home. And being disorganised is easy if you know someone else is going to take care of everything for you. How is he going to learn how to do it himself, so he can do it at school? Model the behaviour you want to see, show your helper how you want her to teach him, create lists that he can use and praise him for the things he remembers to pack up.
Often this type of support starts early. Packing your bags together and talking about what to take; the interaction of planning helps to stimulate your child's thinking and develop their ability to plan, and follow a plan, strengthening their ability to organise. In fact research on computer games suggests the ones that do stimulate children's learning are the ones that encourage them to think about what they need in advance. Planning, an activity computer games are poor at but everyday life is very good at. If your son has not fully developed this thinking process you can always start working on it with him.
Pack bags together side by side. Asking questions of him constantly. "Should we take water?", "Why?", "Oh, yes, that's a good idea", and so on. Add these phrases into your discussions so he starts to feel his thinking is needed and he begins to understand what you will think is a good idea. If he wants to take something that is unneeded you can let him and ask, "Why do you think we need that?", "It is really heavy". During or after an outing unpack your bags and talk about what you used and why it was a good idea to take it or how it might be useful in the future. Putting the needed items in context will develop his critical thinking skills, see the importance of packing the right things and make him feel successful at the useful items he has packed.
Create a list that he is able to use ... PE kit on Thursdays, violin Monday, kung fu kit, piano music and extra snack, Tuesday, and so on.
Demonstrate to the helper how to support him, and not just do the work. Remind her that part of her job is to teach him. Your teaching your son will show her how to stand back and guide him. Also explain to her that it will take extra time for her to do this patiently so relieve her of some work at times so she can stand with him and guide - especially during the busy morning times when you are there to observe and support her efforts. Tell her clearly "I will get my breakfast, so you have time to support his packing, but don't do it for him".