I recently taught a Play-and-Ski lesson for two 5-year old kids. After watching them ski I asked one little girl how she learned to slow down. I got the answer I anticipated: “I just make a bigger pizza.”
From the very early stages skiers learn that a bigger wedge increases resistance to the snow. Many young kids take this knowledge and apply it to all their turns or anytime they need to slow or stop. Occasionally an inexperienced instructor or parent reinforces this big pizza idea and it firmly takes hold. The bigger wedge moves their center of mass farther back putting them farther into the back seat making all the skiing skills harder to apply.