Linking resources in a planning document is an easy way to ensure both co-teachers have equal access to all the class materials. Be sure that you have the material set so your co-teacher has editing access.
Highlight the text and add a comment. Type @ and then their email address. Check the box to assign it to them.
The comment will appear as assigned to your co-teacher, along with your comment.
In their email, your partner will receive a notification about the assigned task. From the email, the highlighted portion and the comment can be displayed. Your partner can answer within the email or open the document and respond.
They can also click the check to show the task is completed.