Bothered by a showing for my house which is for sale

No, you don't have to leave. Is it awkward? Yes, but sometimes life is awkward. The last time I sold a house it was not possible for me to leave when the house was being shown. Luckily it sold over the first weekend we had it listed. I also did not allow a lock box to be put on our house. It didn't feel safe.

Consider yourself validated. I too would be livid if realtors were letting kids mess around in my kid’s room and go through her things! I would say something not only to my realtor but I’d go so far as to call the realtor who brought the people through and say something directly as well about their lack of professionalism. Around here when a realtor brings people through and shows a house they generally leave their business card on the counter or kitchen table so you would know who it was that came through.

My kid wasn’t even two when we were house hunting. If it was at all possible we went to showings on weekdays when she was with the sitter, but there were times we went to open houses, etc. and had her with us. We never EVER let her run wild through anyone’s house or just let her go into other kid’s things or on people’s furniture. That’s just not acceptable.

And WTH with showing up an hour early? I get it that they sometimes line up a bunch of showings back to back, but COME ON! How about a phone call to let you know they’re running really early to give you a heads up? Again, really not professional at all.

Why is it strange to take your kids to a house you might buy? It’s going to be their house too. When we were house shopping this last year, our kids went to most of the houses we looked at. They didn’t come crawl around on beds or go through people’s stuff, which I think is the real problem here, but of course they came to look at houses with us. I wanted to see what was going to feel right to us as a family.

Call you’re realtor and complain, and then call the school her realtor (if they left a card) and let them have it.

It is highly unusual for a seller to be present when a home is shown unless it's a FSBO.

I would guess I have looked at approx 150 homes for sale in my adult life. I can count on one hand the number of times a seller has been present and they have all been FSBOs.

Frankly, they were all such uncomfortable experiences due to the owner's over-estimation of the value of their home and their DIY projects, as well as their hard sell, that when we bought last time, I said I would not go to any FSBO.  My neighbor here had her house for sale when we were buying and initially, we were going to look at that house as well but our realtor discovered the owner would be present (even though it was not a FSBO) and we said we were not interested. It did not sell. She put it on the market again 2 years later and it finally did sell -- our new neighbor was just talking about how uncomfortable it made her to have the original owner "stalking" her as she walked around and how she felt she could not say anything negative. 

OP -- in so far as your situation, I would definitely call and complain. But in my experience, it is a rare realtor who watches the buyers to make sure the kids are not running rampant or anyone peeking in your drawers. Also, in my experience, unless you call the buyer's office to complain, odds are that the realtor will never hear anything from yours about her behavior -- most realtors I've worked with have been far more concerned about playing nice with colleagues or not offending the buyer than protecting your house and belongings. Sorry, to any realtors here, but that has been my experience in 3 different states over the course of 30 years, so I truly do believe it to be the norm. 

I would say one strategy that worked for us was to put everything in our drawers in black trash bags with a drawstring. That way if someone is being nosy, they get no reward for snooping. I did the same with my little girls' clothes in the closet after two adorable dresses went missing after a showing (just put the clothes on hangers in the bag still on the rack). People are less likely to steal what they can't see. 

I will repeat what others have said.

Completely out of line.
Realtor should of rang bell first before accessing lockbox when she/he was that early.
No children should ever be left to explore on their own.

When I was a Realtor, I never showed up early no matter what. You can delay the showing client. That is her/his job.
I never allowed anyone to enter a room without me. We all stayed together. No exceptions.

The showing realtor was completely unprofessional. File a complaint with your realtor, tell her you want a call from her broker, and the other agents broker, and file a complaint with the Board of realtors.

If the clients and their realtor are that classless/clueless, you do not want to sell to them. The closing would be a nightmare. People that show this much disrespect for your personal property would probably complain about everything. And if you get a Purchase offer from those people, I would make sure everything is spelled out in detail, and iron clad. People don't change their spots.

I should have been clearer in my post - bringing kids along is strange in my particular situation. I agree that it is going to be their home as well but, depending on the age of the kids, I find it too distracting to look at homes with kids in tow. We only have a week to look for new home when we move so trying to work around kid schedules, energy levels and the boredom factor while taking in details of the houses we are looking at just doesn't work for me.

This is so sad! We have never had a closing where the other party was present. We went at a specific time and they went at another time.

I always took my kids and left the house while people were looking at the house we were selling. We would just go for a car ride, or get an ice cream cone or stop at a park for awhile then go back an hour or so later.

I’m more blown away there were four car loads of people than I am with the kids running loose. Geeze!

I have felt the same as well! I was in my last trimester of pregnancy when we bought our current home, and I often found that I had to sit and rest. I'd sometimes catch myself sitting on the edge of the bed as I took in the sights of different rooms, imagining whether or not those rooms would work for us. Never have I or would I open anyone's drawers, though!

Our house is currently for sale too and I would be furious if that happened to us.  I would definitely be calling my agent!