I would recommend students clear cache and cookies before taking an exam. let me explain why.

Often, when users visit websites, websites "inject" code to make the website run faster, used for web services such as tracking for ads, etc. However, when users do not clear their cache and cookies (the "injected code", so to speak) every so often, the cache/cookies that canvas generates can in a simplified way, "have some conflicts" with other website cache/cookies.

Fortunately, Canvas provides guides on how to clear your cache and cookies for both Mac and PC:

1. Here is the guide for clearing cache for MAC: https://community.canvaslms.com/t5/Canvas-Basics-Guide/How-do-I-clear-my-browser-cache-on-a-Mac/ta-p...

2. Here is the guide for clearing cache on PC (Windows and Linux):
https://community.canvaslms.com/t5/Canvas-Basics-Guide/How-do-I-clear-my-browser-cache-on-a-PC/ta-p/...

Hope this helps!