I don't go super crazy and have my students look for a leprechaun all day, but I do like to sprinkle glitter on the floor to make believe that one has been in the classroom.
I know some of my fellow teachers have always liked having students make leprechaun traps at home and then bring them into the classroom (great STEM idea), but remembering to do this has not been something I have ever managed to accomplish.
On St. Patrick's Day, I like to arrange my students' desks in the shape of a shamrock and lay green construction paper on the desks. I also like to have a little something special (stickers, bracelets, necklaces, bubbles, etc) on their desks so that when they walk into the classroom they get a big surprise, which of course they love. To add to the fun everyone is in green. It is a low-key festive day, if that makes sense.
As I mentioned, I like spending a full week on this holiday, which means having activities and printables for students to work on. Our writing is usually a leprechaun writing. We write about meeting a leprechaun and tell where we met him; what he looks like; how we caught him; etc. It is a fun writing idea that takes us a few days.
I read lots of St. Patrick's Day stories to my class and I make sure that one of them is a simple version of the history and symbols of St. Patrick's Day. One book I like for this is St. Patrick's Day, by Gail Gibbons. I love to have fun with other books too. Students always enjoy a good read-aloud, but they also like to listen to an audiobook on CD. We listen to some fun YouTube songs as well.
While I actually do quite a bit centered around the St. Patrick's Day theme, most of it is geared toward math. I use packets that I have created. Two of my old-time favorites are my St. Patrick's Day Word Problems and my St. Patrick's Day Roll and Cover packets.
St. Patrick's Day Word Problems
Recently I have created a couple more packets. These are the St. Patrick's Day Adding Tens and Ones and the St. Patrick's Day Math Practice Pages packets.
St. Patrick's Day Math Practice Pages
I hope that you and your class will have a fun St. Patrick's Day and please feel free to check out any resources that you might be interested in.