Unlike the old Google Sheets, the new Google Sheets does not text wrap by default. When students submit paragraph text to a Google Form, or if your spreadsheet data is long strings of text, you may want to toggle the text wrapping on and off. Toggling the text wrap allows you to view a single students full answer.
Control Option O and then W
The keyboard shortcut for text wrapping on a Mac is to hold down the Control, Option and O key. This opens the format menu. After releasing the initial 3 keys, press the W key to choose Wrap.
It will take a little practice to get the workflow down. Click on the first cell that needs text wrapping. Hold down Control and Option and O, release and hit the W key. Read the students work and then repeat the keyboard shortcut to turn off the text wrapping. Use the down arrow to go to the next student. Repeat the text wrap keystrokes.
You can also highlight a range of cells and use the keyboard shortcut to toggle the text wrapping.