My DSS has been brought up living with my DH and his parents due to his mother dying. As a result (and understandably) he's been rather spoilt by his GP's and my DH felt a bit left out of parenting. We got married last year and are slowly getting him to be a 'normal' child. A few of the things he does annoy me but I know aren't his fault, but recently his lying is getting worse. He doesn't really see there's a problem with this as when he lies Nanny and Grandad laugh (they tend to encourage all behaviour that normal parents tell off and that my DH says he was told off for).
On Monday he was meant to do some maths before school but he'd ticked all the sums but not put his workings out (money adding up game). I suspected this was because he'd not done it but gave him the benefit of the doubt when he said he'd not thought to write it down. On Tuesday, he missed 2 sections and wrote down some workings out illegibly. I asked why, he said Daddy had done the 2 sections with him. Daddy hadn't been there. So, he lost a piece of pasta (a reward type incentive for good behaviour)for lying. Then after being cornered he admitted he'd not done the work on the Monday and thought I wouldn't notice. Another piece went, followed by a long talk on why lying isn't good or nice (he's very good at telling you about other people's bad behaviour). Thought I'd got there.
This morning, he did the same bit and put some of his answers twice in a different order for 'find 3 ways to add up to...'. I pointed this out and it seems he once again, thought I wouldn't notice. So, I've just shouted 'you're a liar and a cheat' at him, followed by explaining he obviously hasn't learnt and it made him a nasty person if he lied. He's slightly red eyed but doesn't seem to feel guilt ('I'll try not to lie'), so we're now not going out for the day, my day off work (he has an inset day) is going to be spent doing rubbish stuff to make his life dull.
How can I teach him that lying is not a good thing, ignoring the fact he will always be found out!