I tried this platform and joined finally. Actually the platform is so useful to help kid understanding the concept of maths, and it is really interesting for kid to arouse their interest. And one more advantage, the lesson will have 3-6 students (with same maths level) which can keep kids attentions to learn and play. Teacher will ask each student the question and this can also build their confidence and expression competence. Personally I think this platform is quite good .
baiscally everything you learn at school is trash, not only for DSE. I'm an IB student too. I do agree that IB is less exam oriented and gives u more chances to explore the subject rather than spoonfeeding you with knowledge, but in the end to get a good grade (Level 7) it just boils down to 3 things: Past papers, marking schemes and examinations. It's the same for all streams, not just DSE.