Microsoft has just released a new feature for Office 365 Groups named Group Notebook. The Group Notebook is a OneFile file linked to the Group and it can be used by Group Members for collabarion purposes, share and add ideas, etc. To access this new Groups feature:
Among the available options on the menu of the Group, you will see a new option called «Notebook» appears.
If you click on it, OneNote file in which group members can collaborate opens
Of course, the OneNote file will be also accesible through the management options available in the Site Group: