Ipad how much time

[LoloRupis]

How much time do your kids spend on ipad? My 15yrolds spend 3hrs with breaks my 11yrold spends 30minutes

A day?

Yes

Many things are wrong with so much screen time. First if they are on their iPad, there are not reading/doing schoolwork/ socialising/ exploring the world etc etc....
Then there is the neuroscience of the screen. There are tons of books on that and the changes screens do to your brain, shortening attention span etc .... which will then be reflected in other daily activities.
On an iPad you are using someone else's imagination and creativity instead of using yours. Try to push him into coding, starting with scratch or computer science with CS50 on EdX.

Last but not least, there is an addiction effect and an irritability if you take the iPad away.

A good rule would be no screen during weekdays and restrictions in the weekend.