You don't have to write chapters but just an essay of about 1000 words or so to describe what you have done during your 3 month internship, especially your reflections on your class observations, what you have learned from these classes (e.g if they help improve your learning / communication skills, what you like most/ don't really like...), your recommendation., etc. as guided by Mr Le.
You each are required to hand in your report individually, but for presentation, you both can co-present for about 10 minutes some main points of your report. Please prepare PowerPoint slides and practice speaking in advance.
If you need any further help, please tell me.