I do agree with the "Hello World" activity, it's pretty simple and fun and will get your students a quick idea of coding, see if they are going to enjoy it or not, it can be pretty fun, other than that I have another idea, we did this in the beginning of one of our classes and in a couple of minutes we were all laughing and knowing each other. Students sit in a circle with one of them, or teacher in the middle or to the side, when the one leading standing up says "Small Fish", the students sitting put both fists to their chest, when he says "Big Fish" they put the fists away from their chest, in front of them. You have a lot of flexibility with this activity and can change the words or just say one of them to trick them along with going pretty fast, and if you move your fists wrong you get eliminated from that round. I know it as nothing to do with coding but I hope it helped
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