If you want to look elegant and intelligent, you can try some half rimmed metal eyeglasses, it will make you look smart. If you don't like it, you can try a pair of black plastic nerd glasses. In fact, nerd eyeglasses is the new trend in this years. Many young like to wear. With it, it will give you a intelligent and sophisticated look. Besides, black colored glasses can easy match any clothes. It is a good choices for teachers.
Glasses for teachers shouldn't be too bold or unconventional, thus I think some funky glasses are not suitable for teachers. For example, oversized glasses, cat eye glasses or heart shaped glasses are not good for teachers because they are too bold and unconventional for them. However, a pair of conventional glasses like round glasses is the symbol of a teacher. Now round glasses become fashionable in recent years. If round glasses will look good on you, you can get a pair of them to wear.
Now the most popular glasses are vintage glasses, cat eye glasses, round glasses, aviator glasses and nerd glasses. A pair of glasses that can make you look elegant is what you need. In this case the nerd glasses or some elegant vintage glasses are the best choice for you. You could try some full frame and square glasses and deep color may be better, such as dark brown, black and so on.