If you see that the Chrombook is not typing the expected letters, the keyboard language setting will need to be changed back to US English.
1. Check if the Chromebook is on the correct language (In this example we want US English)
2. In this picture we can see that is it set to CO which is not what we want. 
3. Use the shortcut CTRL + Space to switch it to last used language (Should be US). Otherwise you can use CTRL + Shift + Space until US is selected
As we can see it is now switched to US and keyboard should now be typing the correct letters.
If this doesn't work try this
1. Login to the Chromebook and go to settings (by clicking near time or using Alt + Shift + S)
2. Click gear icon.
3. Scroll down and select keyboard settings.
4. Once in keyboard settings scroll down again and select "Change input settings"
5. Under input methods make sure you remove any other language besides "English (US)". Once the other languages are removed make sure there is a green "Enabled" under "English (US)"
If you are still having issues contact your Lab Manager/ED Tech.