Chromebooks are nice if you want to do basic things like documents/spreadsheets (online or offline).. a basic photo editing app called Pixlr TouchUp.. Online games (and some available offline), browse the web, there is even a web version of Skype available now for Chromebooks.
i own a toshiba Chromebook 2 and it has a good keyboard (comparable to a mac), decent speakers, and nice screen.
all your homework, documents, and even photos etc.. are stored in your google drive account so you won't lose them.
use a Chromebook offline,
https://support.google.com/chromebook/answer/3214688?hl=en&source=genius-rts
i've been using chromebooks since 2012. and thats all i need. but as for you. if you need a computer to do more than what i said.. go with the macbook.
PS.. you can also install ubuntu alongside of Chrome OS but it can be somewhat time consuming and lots of instructions.
EDIT, chromebooks will soon run apps from the google play store so doing stuff offline will be easier.