As a teacher, you definitely can not model the pronunciation of every single word for your students and this is where the importance of web tool such as the ones below is highlighted. Anytime students come across a new word they haven’t seen before, they can check its pronunciation using these tools. In this way they can be sure of how to say it right.
http://www.educatorstechnology.com/2014/05/excellent-web-tools-to-help-students.html