Window sensors easily fooled

@TroxlerFamily many years ago I was a volunteer student guide at the university I attended, a private Catholic institution.  On the tour a father loudly told his wife "Mary is going her. No coed dorms and they will keep an eye on her."  I told him, politely at the end of the tour if that was the reason he wanted his daughter to go to the school, he better make another choice based on what went on in the non "coed" dorms.

I, and many others, have tested ourselves the many sites who claim of vulnerabilities. One with SS2 not being unencrypted, was true but in practice hard to exploit.  The invisible fence exploit was bull, and SS3, which is encrypted, will not be compromised with a garage door open key fob unless you know the exact line of site between the sensor in question and the base.  As far as the magnets, yes, if an intruder can see them, a magnet may work but my glass breaks, motion sensors etc make it more difficult.  And in your scenario, the intruder has an insider to assist...your offspring.

SS, or any system for that matter, is not a babysitter.  I do wish you best on controlling your kids.

As captain alludes to, these systems aren't geared to protect against inside jobs so to speak.

Technology will never solve behavior problems (or at least not for long).  And behavior problems left "untreated", tend to lead to worse problems.

Just an aside, those hard wired "professional" magnetic sensors are also easy to circumvent from the inside, as are the "professional" jamb switches.

what about installing a motion sensor on the outside of the house so that if anything breaks the sensor (climbing in the window) sets the alarm? Put it high enough on the side of the house (assuming the window is a 2nd+ floor) so that it can only be reached with a ladder.

Totally agree with the phone.  We learned that lesson a couple of years ago.

Here is what we did.  Get a SmartThings hub with sensors for the doors/windows you want to monitor.  Also get some smart lights to put in your bedroom (Philips Hue are the easiest to integrate).  Install the system and then setup an automation for the sensor to turn on the smart lights you use.  But here is the catch.  Do not set it for when the sensor is open or closed.  SmartThings sensors have vibration sensors built into them.  Use the automation to trigger if vibration is detected to turn on the smart lights.  You can also get a siren if you want.  This way when the sensor detects movement (opening, being removed, etc.) it will execute the automation.  

We have this on our kids windows.  But you can also use them for other things.  We have one on our washing machine that alerts us when the washer is done.  

Hope this helps.  Kids are way too smart these days.

"motion" sensors (at least SS ones) are not really motion sensors, but "change in heat" sensors.  Thus they are not designed for, and usually don't work in, a non-stable temperature environment like outdoors.  And no other brand of exterior sensor will integrate with SS.  Still, the idea of putting SOME kind of alarm on the outside has merit.  Just be aware that a sensor inside is easy to defeat from the inside, and a sensor outside is easy to defeat from the outside.

If you insist on a technological fix, I suggest an outside camera or two. As someone who frequently circumvented anything my parents tried to do - and that was with my native wit, no internet, good luck!