What does しっかりしてください in this context mean?


I've came across this one page comic panel about an apprentice girl and her
teacher, the teacher then give her a job which he said will be "handy" (手頃な)
for the apprentice but the truth it is actually not.

After she done with her job, the apprentice said this:

> **あなたの「手頃」は本当に信用なりません。しっかりしてください。**

So what does _しっかりしてください_ mean in this? I have known that it has some meaning
like _" Pull yourself together/Get it together"_ but I do not think it will
suit with the above context.




As you can see in [this entry](https://jisho.org/word/%E7%A2%BA%E3%82%8A),
しっかり has various meanings. It is not only an antonym for _confused_ or
_drowsy_ , but also an antonym for _unserious_ , _messy_ , _loose_ , and so
on. しっかりして in a context like this means "get serious and do your job right".
She is asking her teacher to think again and give her a task of appropriate
difficulty.

