I recently got an email account from my school with the schools domain in it. Not knowing i was signed in i looked up some things that could get me in a lot of trouble. I was just wondering can the head of my IT department see this or not. I already cleared it from my recent activity in the google settings.
I didn't know the answer to your question, so I looked it up. I haven't found anything definitive yet, but it looks like admins for Google Apps for Education and Google Apps for Work cannot see your Google search history simply by virtue of being an admin. They do have access to your e-mail account and Google Drive contents and any Google Apps you may use (Docs, Sheets, etc.). There are other indirect ways to snoop on you using techniques such as Deep Packet Inspection and HTTPS Man-in-the-Middle type things, but you'd have to be on the school's network (and especially on school-controlled devices) for these techniques to really be used.
Pro Tip: Try to stop using Google Search, full stop. I highly recommend
DuckDuckGo ("The search engine that doesn't track you") for all your web searching needs. When the Snowden leaks first started coming out in summer 2013, I went through a re-awakening period on how I approach technology and privacy and security, and one of the first changes was to try to be owned less by Google. I've used DuckDuckGo as my default search engine for 3.5 years and highly recommend it without reservation! It was started by an MIT alumnus, and they really emphasize not tracking you and your searches, and the search engine gives great results too.
I love their "bang" system (a bang is shorthand for the exclamation mark, "!"). There's tons of bangs out there. So if I want to look up "turtles" on Wikipedia, I just type in
!w turtles into my browser's URL or search bars, and it immediately passes that search through to Wikipedia. Or
!yt whatever for YouTube. Or
!a stuff for Amazon.
There's other privacy-centric search engines like
StartPage (which uses Google for search results) and
Ixquick, but I haven't used them that much.