A lot of the achievements commonly recognized through certificates are academic. Think back: when you won something like a spelling bee, for example, you often don’t just get a prize trophy; you also get a certificate you can get framed and put on display. So when you want to acknowledge academic achievements, a certificate is a great idea.
This one from Canva includes geometric patterns and lines serving as borders as well as an icon made up of circles serving as a logo, all in a gray, golden brown, and white color scheme. Just change the colors and borders.