Every teacher's worst nightmare is a child getting injured while in their bedroom; partly because you obviously grow to care about your kids but also because it reflects poorly on you as a teacher, and of course a serious injury could affect your career if you could be accused of negligence. There are a number of ways you can act now to make sure your classroom is as safe as possible so that you do not have to worry about any of this.
The first thing you can do is make sure your kids stay in line, especially when moving around the classroom. You may be able to keep their attention while teaching and while they are busy working or playing but when your back is turned do they get up and walk around? By stamping down on anyone getting out of their seats without permission you can cut down on some risk. Also, by keeping toys and games in a completely separate area you can prevent any unexpected obstacles from rolling under unsuspecting little feet.
Your classroom furniture can be a real hazard if too old or worn to operate properly. A child falling off a broken chair is going to not only look bad on you for noticing but will look bad for your school. Preschool equipment is especially important to keep an eye on as children that age are less steady on their feet. Most school furniture should be maintained by your schools maintenance team, but it is still your responsibility to report anything that looks dodgy so keep your eyes peeled.
It may seem very obvious but keeping your bedroom clean and tidy is the best way to keep it safe. With the right kind of classroom storage for keeping toys (especially those with wheels or balls) in one place you should be able to prevent any unnecessary accidents with trips and falls. You should ensure that classroom furniture is kept organized and not moved out of place. Also, with a handy piece of kit to keep all your paintings and glues out of reach when not in use there will be no no excuse for slippery floors.
Finally, if the unexpected does happen, having a well stocked first aid kit on hand to look after any scrapes and scratches should prevent any accidents getting lost after they have happened. Make sure to clean up any blood with disinfected to prevent any cross contamination and to save any squeamish kids from losing their lunch.