Let’s get real for a second: teaching tuck jumps to preschoolers is hard.
They have to have a powerful enough jump to have time to bend their knees up to their chest (without dropping that chest down!), straighten their legs back out to land. Most of their little bodies aren’t built to have big ‘ups’ just yet.
What do we see the most? Tiny little jumps with maybe a bent leg, or if they get their knees up to their chest, they land in a yucky squat/crash that is terrible for their little knees.