500
However, while doing a presentation the students sometimes work as a group, to prepare the presentation, you also know the topic you will discuss, if you have a good preparation, you will make a good presentation.
However, while doing a presentation the students sometimes work as a group, to prepare the presentation, you also know the topic you will discuss. If you have a good preparation, you will make a good presentation. (Comma splice, two independent clauses, following each other. Put a full stop or a semi colon as the two sentences are closely related)