Is it suitable to ask for extra work concerning my bachelor thesis? I study computer science and going to write my bachelor thesis during the next weeks at a very practically working chair.
At my university most students are not able to write simple programs or algorithms (of course they are able to design them in theory).
Because I also work in the field of computer science I have many years of experience in programming. Therefore I think that the tasks I have to do will be very easy and bore me.

Furthermore, during my next semester I have enough time to work on my thesis more than maybe is necessary. I do not want to get a better grade or something like that. I just want to gain new knowledge and work in an scientific environment.

So is it suitable to ask for more difficult tasks and say to my supervisor that I would like to invest more time in my thesis than necessary? Or does it sound arrogant?
The answer to this depends partly on how supportive your supervisor is. In general, yes, it is fine to ask about making your thesis more challenging, but make sure that you do so in a tactful way, and be prepared that you might be told "no". Bear in mind that this is not just something that you are investing your own time in, someone is going to be marking your work, and this has several implications:


If you go well beyond the requirements, the marker may or may not have the required expertise to judge it effectively.
If your extension ends up involving more material, it will be more time-consuming to mark.
The task that you complete will still need to meet certain core requirements, otherwise it cannot be marked fairly against other students' submissions.


These are all barriers that can be overcome - for example, the more difficult task might involve extending the core results of the thesis in an appendix. That way, if necessary in terms of the assessment, the main part can be judged on its own merits. As long as your supervisor is reasonably supportive, have the conversation, and see what they suggest. It may be that you need to bash out an unremarkable thesis in order to meet the course requirements, but that your supervisor can suggest separate, interesting tasks to fill the extra time that you will have.