Why are all my kitchen chairs lying on their sides?

I'll give you a hint. The kids didn't knock them down. I did.
Esther has taken to climbing everything in site. My lightweight wooden kitchen chairs are one of her favorites. She climbs up onto the seat then tries to climb the rungs on the back. As you can probably imagine, this is an accident waiting to happen: baby climbs up chair, chair tips over, baby end up with a concussion from hitting the hard tile floor head first. Possible solutions: 1) supervise baby at all times--ideal, but in a household of three children impractical; 2) removed kitchen chairs to an inaccessible location--also impractical, especially since we need them at least 3 times a day; 3) eliminate the tipping hazard by pre-tipping the chairs. I chose option 3. I'm sure chairs on their sides present hazards of their own (tripping?) but after three close rescues this morning I'll take what I can get.