You know that you are having a 'sucky' lesson when;
1) Pupils are talking when you're teaching.
2) Pupils do not bother even when you shout at them.
3) Seeing uninterested faces.
4) Demonstrating something different each time, sending pupils in confusion.
5) Pupils take turns going to the toilet.

I feel so discouraged. But I ought to have prepared better for the lesson.
Sigh! I feel so sucky now :(