Another outdated thing in the google analytics academy. With very poor instructions on how to find the information.
In order to find the ROI on your ads first click on:
Campaigns under Aquistion -> Adwords -> Campaigns
Then you select the tab “clicks”, now you see the ROAS, which stand for “Return on advertising spend” another word for ROI…
Continue to click on the campaign names to drill down which keyword perform best.