It seems as though angular dimensions have been an issue with SketchUp. Is there a way to show angular dimensions in SketchUP for Schools? This question came up as I was doing an activity with my students.
There isn’t a tool for adding angular dimensions for any of the web based versions. There isn’t a native way in the desktop versions, either. There is an extension that can do it for the desktop versions and angular dimensions are available in LayOut.
Your students could measure the angles with the Protractor tool and then use the Arc tool and 3D text or a label to type in the angle to show it in their model.