Children love to make siren noises whether they're playing with fire trucks and police cars or just trying out all the different noises their little voices can make. Encourage preschoolers to differentiate between high and low pitches by making sirens that start as high as you can make them and end as low as you can make them. Demonstrate this to the children, then do it together as a class. Explain the word "pitch" to students, and explain that they were just making high-pitched and low-pitched sirens. Once they understand the concepts, "test" them by alternating from high to low sirens in when you shout the words "high" and "low."
Assign a song or drama with two characters--one who has a very high-pitched voice and another who has a very low-pitched voice. Make sure that the voices fit the characters. For example, a big, tall father would have a low-pitched voice and a little girl would have a high-pitched voice. This will help children remember the pitches. Give students roles to play in the song or drama, but state that they must speak or sing in the right pitch for their character. Practice what each character sounds like as a class before doing the activity. After the activity is done, introduce the students to the idea of high and low voices.
If you have music time during preschool, integrate high and low pitch into it. Have children sing songs that include high and low pitch notes, and explain the differences between each. If your music time is accompanied by a piano or guitar, play low notes and high notes and have children identify which is which as part of a game. For example, when you play a low note, children have to sit down, or "go low." When you play a high note, they have to stand up, or "go high."
Play recorded music of children singing children's songs and have children listen for the singers' pitches. You might have children move their hands from high to low while listening to the song to indicate when singers move from high notes to low notes. Or you might just ask children to sing a part of the song they just heard and tell you which words are sung on higher notes and which are sung on lower notes.