Research has shown that lessons which engage children are often more effective and allowing children to get involved in a task can help aid their learning. Obviously it is not possible to get children actively involved in everything you teach them, but most lessons can include a certain amount of practical time.
When it comes to teaching maths, some children can find it quite boring and can easily get distracted. Try setting them work where they work in groups or pairs to solve a problem and try and make it fun. Often by using items for them to count with or sort, it can help them to get involved and often seeing something makes it easier to understand than reading about it in a book.
The internet is full of great lesson plans and material which can help you make your lessons more fun for all ages.
If you are working for a teaching agency, then they may have aa portal which will allow you to download lesson plans or material to use free of charge.