Learn ArcGIS
For Learners:
The Learn ArcGIS provides collections of curated content to guide you in your discovery and exploration of ArcGIS capabilities and products. From beginners and students to advanced users and educators, the Learn ArcGIS can help you learn, teach, and advance your GIS careers. Use the knowledge you gain from the Learn ArcGIS Hub to help the GIS community change our world for the better.

Their Lesson Gallery allows you to explore all the lessons they provide. You can create your own filter to sort lessons by capabilities, products, and more to discover the ones that suit you.
For Educators:
Learn ArcGIS also provides a Teach with GIS Implementation Guide for Teachers, Schools, and Districts. Their goal is to support you in helping others learn about making maps and solving problems using the tools and data included in your GIS. All of the lessons are free to download and share. You can explore the Lesson Library and select exercises that fit the experience level and subject matter of your class.