I agree with the poster on the other thread - the key is variety! When I student taught 2nd grade I had a code word written on the board each day (ie

eanut butter). When I said the word the children would
whisper back "jelly" or.....code word "roller" and whisper back, "coaster". They loved it and it really helped focus their attention!
Now that I'm in 1st I use many of the things the above posters suggested, "1,2,3 Eyes on me", whispering "If you can hear my voice put your hands on your head, etc." , light flashes, "Give me 5" AND clapping patterns. Looks like I'm going to be adding "hocus pocus" and "hands on top" to my signals this week! I love them!
Good Luck!
