Pitch level conducting focuses the attention of the children on the melody of the song and the up and down quality of pitch. This type of conducting is done by holding your hand in front of you in a flat position, then moving your hand up and down in precise movements, as the melody rises and falls. If the notes are repeated, just bounce your hand forward with each repeated note. You can add variety by moving your hand up and down your other arm or by showing the children how to use their whole bodies in an up and down movement.
Pitch level conducting can be very helpful to children when they are learning a new song. People who are very musical seem to have a natural ability to hear the tones of a melody. The rest of us struggle with this in varying degrees. The Church expects all of us to actively join in the singing. This is especially true in Primary. We sometimes chide the children if they don't sing. Sometimes we observe children just mumbling the words and not singing out as we expect them to. Possibly these children are unsure of the music. As choristers, we often focus on learning the words of the song and expect the children to pick up the music on the fly. If children are not participating as I think they should, I take it as my cue to review the melody of the song. Usually, when the children know the words and the music well, they sing willingly.
Pitch level conducting is not as commonly used as it could be. When I was a child the primary chorister used this method almost all the time, but you don't see it much anymore. Perhaps we just don't think of it. I think maybe it is because we are self-conscious about our ability to do it well. Studying the music ahead of time will help, so that you know how the melody moves. If you don't play music yourself, the pianist can help you. Practicing the technique at home before using it with the children will make you more confident. I also think that it helps to be deliberate. I have a number of methods on a list that I read through as I prepare to teach or review songs. If I haven't done this one in a while, I consciously choose to do it. I have also found that I am more comfortable using something other than my hand. While my hand is "handier" and takes less time, I sometimes use a ruler, and sometimes I hold it between both hands. I have a can with popsicle sticks for the children to use in the same way.
Give pitch level conducting a try. You don't have to conduct the whole song this way, but it can be very useful for phrases that musically complicated or that have abrupt changes in pitch. It becomes easier to do as you actually do it and it will make a big difference in helping the children sing more accurately.