Once you’ve selected a language the hard part should be over but you will also get lots of solutions on the best IDE to use for teaching Java. I don’t think there is any one best IDE for teaching Java from what I’ve seen. There are lots of good options I would just stick to one that many teachers are using.
Keep in mind that most Java IDE’s were not written for students they were written for developers spending 40+ hours a week looking at 1000’s of lines of code. What that means for teachers is that almost any IDE provides way more features than you need. On my last teaching project our team narrowed the IDE down to NetBeans and Eclipse – I think they are both just fine.
If I do a monster.com job search on “Netbeans Java” compared to “Eclipse Java” I find way more jobs for Eclipse. In my mind that means that industry is using Eclipse more than NetBeans, however, YOU ARE NOT PREPARING KIDS FOR INDUSTRY! Your job is to teach programming and you should choose the tool that you think will help you do that the best.
Sometimes you are limited by what you can have installed at school – don’t let that discourage you if you can’t get exactly what you want. It is also nice to have something that kids can easily install at home. It can take time to get everyone up and running with a working IDE. I recommend you start your course with CodeAcademy or another free resource that lets them get learning Java without having to install anything.