What is the best free LMS for schools which have accounts for parents, students, and teachers?
So, answering to your question, it is difficult finding a platform for free that accomplish with the minimum requirement that the education field required, but not impossible.
Paradiso Free. This LMS has a variety of features: gamification, social learning, multi-tenant, certification, etc. A great LMS for small businesses, but not a good choice for larger ones. It allows a maximum of 50 active users.
My recommendation is using Paradiso LMS, free version, they can give you enough tools to satisfy your education services.