I would start out with some kind of dividend paying mutual fund in their own IRA. Also put some in CDs and bonds in order to teach diversification. Some of the initial investment is as little as 250-500 dollars for mutual funds. They can arrange to have earnings used to buy more shares every so often. Also kids should be told to develop a second source of income by working part-time or small investing on their own. That could be a rental property. If they want to speculate for money with collectables, house flipping, car selling etc make sure they do not put their entire savings into it. If they succeed a large chunk of that money needs to go in a conservative investment for use in retirement only.
The days of a 30 year career, gold watch and pension are done, gone, cahput etc. They are on their own so they need to learn finance and taxes EARLY in life.
I say as a life lesson period try to do as much as they can on their own. Do not pay someone to do every little thing. There is no reason to have your taxes prepared if you file an ez form. You shouldn't need a mechanic to check engine oil, air in the tires or check hoses and wires for cuts, holes, wear marks etc. They should be able to swing a hammer and use an oven. Retirement is as much about independence as much as anything else.