This is a great filler lesson for days when you're not using the textbook. I mainly use this one with my 6th graders but it would probably work with 5th graders too. This lesson aims to introduce Internet Slang and chatting culture from the USA. Feel free to change it to whatever English speaking country you're from. Attached are the lecture power point, accompanying worksheet, and a quiz game to review the content as well as test some trivia.

regarding the quiz game, some of the questions aren't mine and i didn't use them in my lecture. i co-opted this game from another person. change them according to your requirements.

I've use something similar with middle, and high, school students. Usually it gets the attention of like 80+% of the class. They're always interested in stuff that kids their age will do.