Non-English keyboard letters
I use Duolingo on both a Chromebook and a Linux (Ubuntu) PC. I finally found that I can make the grave marks on the Chromebook by turning on the US INTL keyboard (and in Languages I found Scottish Gaelic, but it isn´t the keyboard and I don´t know what it does yet). In Ubuntu (where I first needed it), I followed advice I found online and used the UK-extended-Win Keys keyboard. I used the US INTL on the Chromebook because mine does not have the UK-extended, and US-extended did not work for me.
To make the grave mark such as in cù and bò with the US INTL keyboard, press the key next to the [1 !] key (it has the grave mark as well as tilde), then the vowel you are marking.
With the UK -extended-Win Keys keyboard hold down the right Alt button while you press the vowel.
I hope this helps someone else as we try to practice good spelling.
Use the numpad and alt keys:
à = alt+0224
ò = alt+0242
ì = alt+0236
ù = alt+0249
è = alt+0232
This is what I use anyway. I'm typing on my keyboard at work, but when I get home I'll modify my keyboard layout, to something more practical. Perhaps macros are the way to go - dunno. Suggestions?
You can also create keyboard shortcuts to replace a combination of keystrokes with an accented letter (or anything else). For example, my shortcuts replace a vowel followed by the accent character (a`) with à. You could reverse it, or create any combination that works for you. It makes life much simpler. ;-)