Yes, you told us you have to use a Chromebook too… for your psychology class!! … Damn.
Very smart to do it with pictures. This way the information will less likely be analyzed. Besides pictures, what anyone can do, is prepare texts in a separate editor and - when all ready - copy/paste them all at once and then submitting.
I don’t know exactly what personal information is sent to the server this may vary depending on software/website used. But if there is a keylogger at work, the way you type when e.g. describing a moral dilemma (hesitating, correcting, or typing the answer with conviction), this may say a lot about your psyche.
There is a tool, but it is for mobile android phones, that captures your text typing in any app, and then before it will be sent, it encrypts the data. This way no legible information is sent over the wire. But it requires someone on the other side to decrypt the data again, so you’ll need acceptance of that method. This tool is on our awesome-humane-tech list, and called Oversec
For longer essays, if the software allows hyperlinks, you could create a PDF document with a password, and link to that, or attach it as a file. Then send the password separately to your teacher.