As part of their curriculum, several STEM courses include practical sessions where students have to complete a number of tasks under the supervision of several teaching assistants (TAs). For online classes, or lectures that take place across several venues concurrently, it is challenging to provide assistance since it is not always possible to have physically present TAs. In this paper, we investigate the use of web technologies to address the problem of remote assistance in practical STEM courses. We combine existing tools to implement a system where TAs can remotely assist students present in different locations in real-time. We have tested our implementation, and the results show that this is an effective approach, particularly for online lectures.