Do not think it worth while to proceed by concealing evidence, for the evidence is sure to come to light.
Never try to discourage thinking for you are sure to succeed.
When you meet with opposition, even if it should be from your husband or your children, endeavour to overcome it by argument and not by authority, for a victory dependent upon authority is unreal and illusory.
Have no respect for the authority of others, for there are always contrary authorities to be found.
Do not use power to suppress opinions you think pernicious, for if you do the opinions will suppress you.
Do not fear to be eccentric in opinion, for every opinion now accepted was once eccentric.
Find more pleasure in intelligent dissent that in passive agreement, for, if you value intelligence as you should, the former implies a deeper agreement than the latter.
Be scrupulously truthful, even if the truth is inconvenient, for it is more inconvenient when you try to conceal it.
Do not feel envious of the happiness of those who live in a fool’s paradise, for only a fool will think that it is happiness.
I find this to be of use not just for teachers but for rationalists in general. #8, especially, is an especially eloquent formulation of Aumann's Agreement Theorem.
This doesn't seem to be specific to teachers at all. How about these instead (off the top of my head)?
Don't try to teach those who do not wish to learn, or students who did not choose to attend your lessons. It's a waste of time and will make them hate you and the subject matter.
Choose your metrics carefully. Treat exams and other common tools as a cached thought. Remember your students will always optimize the metric you choose, not the one you had in mind.
Know your goal. "To teach someone X" is not the same as "to help them earn a degree" or "to comply with mandatory education laws". Goals are arational, but do not be confused about yours.
Fill in this commandment, due next Monday.
If you do not know the answer, admit it freely, but be prepared to learn and explain it during the next lesson.
Unless teaching children or unwilling students, you should not find yourself spending time on "discipline".
If in doubt, tell your students to read the Sequences.
Both you and the students are allowed to have fun during lessons. This doesn't make them less "serious". Most people have trouble concentrating; find ways to help them.
If your students are "cheating", it's not their fault: you are not providing them with the right metrics, incentives, and rewards.
It's OK to only have 9 commandments if you can't think of a worthwhile tenth.
Betrand Russell's Ten Commandments for teachers.
I find this to be of use not just for teachers but for rationalists in general. #8, especially, is an especially eloquent formulation of Aumann's Agreement Theorem.