Take time so students learn the hand signs correctly from the beginning. It’s important for them to learn the hand signs in correct relation to their body. Doing this from the beginning is more effective than waiting and letting students gradually catch on through observation. Additionally:
- Practice changing hand signs just slightly ahead of the beat so students see the next pitch just before they do it
- Add dynamics, especially when certain students are too loud or too soft. Use crescendos and decrescendos
Perhaps you prefer relaxed thumbs that are parallel with the fingers* as I do. This makes for a clean look and a smooth transition between hand signs. To correct a student whose thumbs are up, turn in their direction, smile, and put your thumbs up. As you lower your thumbs, click your tongue, stopping when thumbs are in place. They will copy you and lower their thumbs, too. Use this gentle reminder whenever needed. Alternatively, if I'm in a playful mood and anyone’s thumbs are sticking up, I might say, “Thumbs up looks like a shark. Who was the shark in 'Finding Nemo'?” (Bruce)