Greetings @sndbox-alpha. Thank you for the opportunity that you give to convene with educational rigour and science publications to evaluate them. https://steemit.com/steemiteducation/@ulisesfl17/research-holistic-applying-constructivism-to-create-a-slow-sand-filter-in-the-school

I leave my contribution to undergo review desire that the project be expanded and have immense success. Thank you