This is a new feature that we have recently launched. You can currently export data to an Excel spreadsheet from the Students page.
To export student data to a spreadsheet, simply click 'Export to CSV' from the students tab.
We are working hard to add this feature to more areas of the teacher platform and you can expect to see it in the coming weeks and months.
Until then, the easiest way to extract the data is by selecting all the student data and using CTRL+C or CMD+C to copy it into your sheet. We understand that this is not ideal, and would need some further data cleaning. We're sorry that this is not the perfect answer and will try our hardest to get the functionality added.