There is a daycare career, available with the Generation Expansion. Carl's guide has some great answers.
http://www.carls-sims-3-guide.com/generations/daycare.php
If you already know about this career and are looking for a place to send the toddlers, I don't believe there is one, but you could always (at the risk of the game forgetting your child's relationship to your adult sims) set up a neighbor's house and refurb it into a daycare, then just move them over with either the NRAAS Mover mod or by taking the adult with them, then placing only the toddler in the neighbor's house, and moving the adult back. The downside to this is also that you would only be able to play one family at a time and in TS3 (again without mods) time doesn't stand still for the town (there is a way to get TS2 style aging with another NRAAS mod though). If you're okay with playing separate families you can also disable aging and have the toddler learn while you play that family for a week and then move them back.
Starlit Shores (came with the Showtime expansion) does have a really nice community daycare lot and you could also copy that lot to bin, add it to your current town or move to Starlit Shores and just have one of the sim parents take the toddlers every day (Ooo or go completely crazy and get a simbot or create a future bot with the childcare trait chips and just have them go with the toddler every day!)
