Very angry 5 year old

Chuchoter

I mind this little boy twice to 3 times a week with his little brother (2) and sister (4). They're really nice kids most of the time, but sometimes the boy just goes into an absolute rage over tiny little things, its actually scary. He was telling his sister to go down the slide backwards (neck-breaking time!) and I told them no, and then they tried it again, and I got annoyed. Then he picked up a doll (those big heavy ones that talk?) and said "I'm going to throw this at your head and break your glasses" and he was completely serious. Eventually he put it down and was quiet, and I said sorry for yelling at him.

Then (about 20 minutes later) we were playing with this dolls house thing and the sister took one of the little toys off him and he picked up a chair and threatened to throw it at her (it was kids mini furniture, but wood and heavy) and wouldn't put it down. He then eventually said I'm so angry because my grandad is dead. Is this just an excuse (are 5 year olds capable of that?), how do I deal with it and should I tell his mum? I'm worried about going back now this week in case he actually does throw something and really hurts someone (including me!) or breaks a window, and then I get blamed. I'm normally so good with kids and I have 5 years babysitting experience, so this is unusual.

The Big Red Button

I'd definitely discuss it with his parents. For a start, it would be good to have a chat with them about exactly how they go about disciplining the children when they act up - time outs, etc - so that you can keep it consistent. Especially when you're minding them so regularly.

Also he's old enough that you should be able to reason with him about why he shouldn't do certain things, rather than just telling him not to.

The thing about his grandad is definitely something his parents should be made aware of - he might not have said it to them, as perhaps they get upset talking about it and he may have picked up on that. But it's something that they should know.