Fidgets can help some kids with ADHD focus better. They're not "one size fits all," however. Different types of fidgets can meet different sensory needs. You can see which work best for your child, and then talk to the teacher about using them in class.
A Mind Map, created in PowerPoint, that works as a poster or as a mini presentation that could be used as part of staff training or to build awareness. This list of difficulties is not exhaustive but is a flavour of some of the issues that can affect students with ADHD.