My young son and i both have our own ipads which share the same (mine) apple ID. is there a way to configure them so he can't see my browsing history (and NO- it's not porn), text messages, etc?
Can this be done with both ipads using the same apple ID?
The short answer is "no," it's not easy to share an iCloud account, make some information separate, and keep it that way. It's far easier to have separate iCloud accounts.
It's not clear why you want to keep using a single iCloud account - you may be operating on old information. Since the introduction of Family Sharing, there's no particular reason not to have separate accounts. Parents have a variety of tools that allow them to manage kids' activity.
If you're dead set on using a single account, what you can do is limit your use of some iCloud services, and for iMessage/FaceTime you can add additional email account names that will allow you and your son to have separate identities in iMessage and FaceTime. However, if settings get changed (inadvertently or intentionally), then this strategy can go out the window.
As far as Safari history goes, just turn off Settings > [name] > iCloud > Safari. This is the feature that shares browsing history/open windows/tabs across multiple devices.
For iMessage and FaceTime you can add an additional email address to your Apple ID account for your child's use - you'd then setup iMessage on your devices to view only messages sent to your/your child's email address and/or phone number (Settings > Messages > Send & Receive > You can be reached by iMessage At/Start New Conversations From).
For Contacts you can setup separate contact Groups for each of you, but it's still very easy to mess things up and have the wrong contacts in the wrong group.
Similar for Calendars - setup separate calendars for each of you, and only view the calendar(s) you wish to see. Same downside as for Contacts, though.
Altogether, though, it's not an easy way to manage things. A separate account for each makes more sense. That can be separate iCloud accounts, or you can use other cloud-based email services that provide contacts, calendars, notes, etc., like Gmail, Yahoo, Outlook/Live/MSN, etc. - one of you would use iCloud for contacts, calendars, and notes, the other would use their mail-based contacts, calendars and notes.
All these tips, and lots of complications, settings (and possibility for intentional/unintentional eavesdropping)... all to avoid creating a new, free iCloud account for your child.
Apple's general Family Sharing support article:
https://support.apple.com/HT201060
Apple's support article on Family Sharing Child Accounts:
https://support.apple.com/HT201084
