Sid Williams, formerly named Josh, is the main character of Sid the Science Kid. At four or five years of age, Sid is the eldest child of Mort and Alice Williams and the brother of Zeke Williams. Sid's most prominent character traits include learning, observing, questioning, and general inquisitiveness. Sid is one of four students enrolled in Susie's class.
One of Sid's favorite items is his toy microphone. He uses his microphone to deliver stand-up routines to his stuffed animals (including his large stuffed dinosaur Arnold Harrington, and his bat-and-wobble penguin Dr. Leonard Beaks). The microphone has 4 buttons to deliver pre-recorded laughter, applause, an echo-effect and cow-moo-moo noises. He often uses these features to punctuate his delivery.
Sid's mother drives him to school each day, and his paternal grandmother picks him up at the end of the day. At school, Sid plays with his Best Friends - May Prewell, Gerald McIntosh, and Gabriela Ramirez. While playing on the playground, Sid will often survey his friends on different topics as part of "The Sid Survey". He also participates in "rug time" discussions, keeps a science journal noting the results of classroom experiments in the Super Fab Lab, and will role-play and play dress-up with the other students during playtime. Sid occasionally goes on dates with Gabriela or May after school.
Sid Williams comes from an ethnically-mixed family; his mother is an African-American Christian and his father is Jewish. Sid's family celebrates Christmas, Hanukah, and Kwanzaa. Sid's paternal Aunt, Aunt Irene, lives in Minnesota.