Lemma
It is our hope that your favorite high school teacher would become excited about Lemma and send our email to the parents suggesting that they take a look. It would also be very helpful for future adoption to have a community of excited teachers.
Lemma  Wikipedia https://en.wikipedia.org/wiki/Lemma

Very soon, Lemma will launch a crowdfunding campaign to fund the development of a course in high school Algebra. The success of the campaign will be determined almost entirely by the quality of our presentation and the strength of the community that we will have developed. So, we need your help!

Lemma, Inc.
ELearning Company Size210 employees Wynnewood, PA

About us
The Lemma platform aims to usher in the next generation of online learning systems by creating a platform capable of scaling and, in many important aspects, improving, the oneonone teacherstudent model. Lemma’s goal is to create a complete learning platform with everimproving adaptive features. To this end, Lemma will bring a select group of authors and learning theory experts inhouse who will be working closely with the platform developers to create a complete universe of coherent and crossreferenced content for STEM subjects. This close collaboration between the education experts, the authors, and the developers assures coherence of content and its uniform quality across the platform. Lemma’s everevolving content will be delivered by a stateoftheart learning platform that supports the aggregation of the content into various educational units (worksheets, tutorials, courses), augmentation of content with elaborate communication and engagement features, an integrated learning management system (LMS), advanced computer aided assessment (CAA) tools and gradual incorporation of adaptive learning techniques. This holistic approach is in stark contrast with all other players in the area of education which typically focus on one of the elements required to build a truly effective learning platform.
Math TheBeautiful on YouTube
Math TheBeautiful
Description: In this channel, I share my unique approach to mathematics subjects of all levels. I'm currently working on a Linear Algebra series. I will soon add a series on Calculus, Algebra, PreCalculus and Probability, as well as more advanced subjects such Differential Equations, Applied Mathematics, Numerical Computation, Calculus of Variations, Calculus of Moving Surfaces, Shape Optimization and other subjects. I believe that the role of the teacher is to focus on the very essence of the subject without obscuring it with excessive rigor and formalism. Mathematics Is Beautiful and sharing that vision is my main goal.

Math TheBeautiful
14,122 subscribers 1,596,343 views Joined Dec 19, 2013 
My Tensor Analysis book is finally out. As my colleagues and students know, Tensor Analysis is my favorite analytical technique. The last three chapters of this book are devoted to the Calculus of Moving Surfaces.
Solving the Wave Equation in 1D by Fourier SeriesPublished on Apr 23, 2017Complete playlist: http://bit.ly/PDEonYT Go to Lemma http://lem.ma
Other than http://lem.ma, I recommend Strang http://bit.ly/StrangYT, Gelfand http://bit.ly/GelfandYT, and my short book of essays http://bit.ly/HALAYT Linear Algebra is one of the most important subjects in mathematics. It is a subject with boundless practical and conceptual applications. Linear Algebra is the fabric by which the worlds of geometry and algebra are united at the most profound level and through which these two mathematical worlds make each other far more powerful than they ever were individually. Virtually all subsequent subjects, including applied mathematics, physics, and all forms of engineering, are deeply rooted in Linear Algebra and cannot be understood without a thorough understanding of Linear Algebra. Linear Algebra provides the framework and the language for expressing the most fundamental relationships in virtually all subjects. This collection of videos is meant as a stand along selfcontained course. There are no prerequisites. Our focus is on depth, understanding and applications. Our innovative approach emphasizes the geometric and algorithmic perspective and was designed to be fun and accessible for learners of all levels. 
Pavel Grinfeld

A Few Of The Other Tutorials On YouTube
offered by Math TheBeautiful
Published on Apr 24, 2017 Complete playlist: http://bit.ly/PDEonYT Lemma http://lem.ma is the place to be!
These videos represent an entire course on Partial Differential Equations (PDEs). A strong emphasis is made on the Linear Algebra (http://lem.ma/LA) structure of the subject. 