thank you so much for your replies.
we will be easy on him for the next couple of weeks. but we will go and have a chat with his teacher if things get worse or if they continue for too long.
atm it seems that his bad behaviour is only at home (when all four of us are together; he is much better one-on-one), as we haven't been called in by his teacher, which i am sure they would have done if he'd behave like this at school...
he is a very sensitive little boy: he does not like change in his routine very much, and is very aware of his own limitations. it does not help that some of the children in his year can already read and write (although i know this only from ds1 saying so, so i have no idea of how good they are at it exactly). i have told him that this is something that he will learn during the year and that he can actually already recognise certain words (apple, stop, juice, mango, banana, and his name, his brother's name etc). i have always tried to stress his qualities, rather than talk about the things that he thinks he is no good at. eg he is very good at maths: adding up, and now he even understands numbers less than zero.
he asked me yesterday when he was going to know everything, as he is not the smartest kid in his class and his friend knows everything already. i said that nobody knows everything (according to ds1, i don't, but dh does ), but that school is all about learning things but having fun at the same time.
it was good to read that we are not alone, and very helpful to get tips such as yours, slayerette: he loves cooking.
he is actually home sick today (some stomach bug), and i am with him, so i'll try and see if he is up for some home cooking session. atm he is still too weak to do anything but being under his blanket and watching some telly, although he did tell me that he'd like to do some drawing and lego with me later.
so, i'd better be off and look after him... thanks again, i feel much better after your replies.