You need to understand that we don’t use English for our day to day conversations. Children are just learning to be familiar with English. Is it possible to teach them the language through computers ? I prefer keeping the lessons offline as far as possible.
The way I learned and internalized English, was through programming and a vocabulary trainer/flash cards at around 11 years old. So my advice would be: find something they find interesting and provide them with mostly English resources to learn that interesting thing, while also starting to learn basic vocabulary through flash cards.