Why is it grammatically incorrect to say
We would like to discuss about the matters at hands first.
But it is alright to say
I will think about what you have said this morning.
What I've heard that the word discuss is treated like consider and investigate. It makes sense that about cannot be placed with consider, e.g. it sounds weird to say "I'll consider about this relationship."
So what are the words that will have the same effects with discuss, consider and investigate? What makes look and think so special that about is grammatically correct to be used together with them?