1. UNLOCK BADGES：allow students to unlock certificates, badges, or achievements they can proudly display. 2. UNLOCK CONTENT：When students level up or hit certain milestones, unlock new challenges, tools, or powers that help them grow further in their learning.

resource tiering (such as Rare, Epic, Normal, etc.), the goal is to make students excited and proud when they unlock or gain certain skills. The tier system adds an element of rarity and achievement to each skill

1. 不同的技能需要有不同的等级 2. 随机的奖励，随机的题目 随机性，差异性，实用性