The Opening song (always a song about Heavenly Father or Christ and His Gospel) calls the meeting to order and signals when to focus on the speaker at the pulpit for announcements. The Prayer song signals to fold your arms and get ready for prayer. The Reverent Song can be used at any moment to transition from a louder activity to a quiet story or talk or a special Guest's message. The "wiggle" song is important to use as a change of pace or for when the children just need to move. It is important to have variations in doing a wiggle song - fast, slow, loud, soft, high, low. It can be done with broad movements or completely silent or anything in between depending on what needs to be taught or accomplished. "My Hands" is an excellent choice because it ends quietly with the arms folded. When the children understand that there are plenty of different activities in Primary including movement and creative expression, they are very willing to sit patiently through the periods of quiet time.
NEVER --- AT ANY TIME --- and I repeat --- NEVER should the singing be allowed to get out of control with yelling, wildness, or using obnoxious sounds, disrespectful voices or motions. (Most kids, when given the chance will always opt for silliness over respectfulness. So never give them that opportunity!!!!) Children naturally have light high voices and should NEVER be encouraged to sing louder than their instruments can produce healthfully. If children are encouraged to yell, they do not learn to LISTEN to and match PITCHES.
A good music leader should ALWAYS try to teach in-tune singing!!!!!!! The children should be encouraged to fill up with air and use their support muscles to sing with beauty. That is true power. They should be taught that music can be a conduit to the Spirit. Through their lovely in-tune singing, they can invite the Spirit to be with them in Primary.
I have visited many, many Ward Primaries throughout the Church and a common problem is that the inexperienced Song Leader does not realize that by encouraging the children to sing loudly and always do big actions, they are creating their own worst nightmares. They wonder why the children are so irreverent and uncontrollable and why they do silly things like jump up when they sing "Jesus wants me for a Sun -- BEEP!" Save the silly actions for the wiggle songs and cultivate an attitude of respect for songs about Jesus Christ, our Savior and Redeemer.
I know through many years of practical experience that these principles work. My heart aches to see the rising generation growing up without learning to feel and know the Spirit through these beautiful Primary songs. When children learn these songs, they can draw upon the powerful yet simple gospel messages they contain as they need guidance in their lives.