Default mouse sensitivity on school mice is terrible. Go to settings in the main menu. Drop your sensitivity to 3.5 (vertical) and 4.0 (horizontal). Because school monitors are usually low refresh rate, lower sensitivity helps you track heads with the shotgun.
The legitimate Classroom 6x site usually has a search bar. Type "1v1." If the game doesn't load, look for a red button that says "UPD" or "Proxy Mirror." Clicking this refreshes the iFrame (the window holding the game) to a new server. classroom 6x 1v1 lol upd
The best "UPD" links are rarely on the first page of Google. They are on Reddit (r/unblockedgames or r/school gaming). Search for posts from the last 7 days. Look for comments with phrases like "mirror link" or "new domain." Default mouse sensitivity on school mice is terrible