Non-judging is a primary attitude of mindfulness.
This is being in what is known as the ‘observer mode’. We become an impartial scientist who is merely observing an experiment without labelling what is happening as being good or bad. It simply is.
You are merely being a non-judgmental witness of your current experience. Non-judging requires us to suspend any judgements and comparisons. We do not judge the current experience based on past situations or future expectations. We simply accept the present moment as it presents itself.
If you are watching a sunset, you don't have to compare it to a sunset you saw last week. You merely appreciate this new sunset that you are watching it now and enjoy it fully. Likewise in your teaching, don't compare today's lesson experience with yesterday's.
As you start to practise more mindfulness in your teaching, simply observe this judging quality of the mind. Notice what thoughts are coming to you and merely observe how many thoughts are steeped in judgement.
(Material inspired by Moodle Academy An Insight into Mindfulness course)