Build web application & mobile app for learning (Math)

We are looking for reliable web developer or team to create this website.  
The backend end must be up-to-date technology, and website must be fast, mobile responsive and scalable (e.g. if I make my screen bigger must adjust correctly) - the usual stuff of a good developer will take into consideration without we telling them.

Need someone who has created this before and has experience and know what is important and what is required.

Required to Build web application & mobile app for learning.
Our online platform empowers students to Learn ,Practice ,Test & Master Mathematical skills. excellent Analytical engine , reporting module and collaboration between students , teachers & parents are powerful tools to make sure students are in complete control of their coursework and others can easily monitor and guide wherever required.
LEARN : Concept Learning through rich media
PRACTICE : Application of concepts through different tools
TEST : Robust adaptive testing

Application to be built in latest technology stack using Cloud :AWS

PHASE I DEVELOPMENT
• Login Course Activities ( Class wise /Topic wise & Practice) similar https://uk.ixl.com/maths
• Test
• Social Media Integration
• no screen recording & no screenshot & copy paste
Admin :
• Create Curriculum
• Add Question
• Questions
• Preview Question

PHASE II DEVELOPMENT
• Registration
• Video-based Content
• Live Tutorials (Live Streaming) and Interactive/Webinars Sessions
• Social Media Integration