From my experience in Alex (at an admittedly somewhat dodgy school) and from reports I've heard from other teachers with experience in the Middle East/Egypt, the inverse maturity rule appears to apply. The older they get, the more immature the students seem to become (especially for the boys). So you have 3rd graders who are fairly mature and high schoolers that wrestle in the hallway, give each other wedgies and generally behave like idiots in class. That being said, many of them were also very nice, responded to teachers that were able to engage them and seemed to appreciate the extra efforts that some teachers made to promote learning, establish extra-curricular activities etc. So, with Year 5's you should stand a fighting chance. If you are able to strike a balance between good humored/caring and clearly establishing how much shite you will accept from them, you will be just fine. Be energetic, creative, engage them with lots of projects and get them on board with you. The teachers I saw that had nightmare times, were also the ones that had students reading aloud from the text book and doing worksheets every day.