I have involved my son in jobs right from the start, he started hoovering for at 8 mths when crawling, he loved the hoover! he could put the washing in machine, put in powder and start it by 20mths. Now he's five and he hoovers his room, takes his plate into kitchen, waters plants and occasionally does some washing up. he loves it (most of the time!) he thinks its normal for everyone to help around the house and i am hoping this means he'll always do it!
I would say a seven year old could do washing up, hoovering, help with cooking, hanging clothes on line and sorting out clean clothes, they usually love it still at that age. my friends girl who is seven does my washing up for me because she wants to!