Context: Since online discussion forums are widely used in Distance Learning platforms, instructors ought to be aware of what is happening in them. Goal: Our study aimed to identify scientific studies that investigate awareness in online forums in Learning Management Systems (LMS) and Massive Open Online Courses (MOOC). Method: We conducted a systematic mapping to identify, filter, and classify primary studies. Results: We selected 51 papers and categorized the difficulties faced by discussion forum users into four groups: visualization, motivation, structural, and accompaniment. In addition, we identified six types of awareness elements: informal, group-structural, workspace, social, task, and concept awareness. The results were divided into two types: system/framework and approach/investigation. Conclusion: our study provides an overview of the state of the art and challenges concerning awareness information in online forums and may guide future studies and tool development.