The smaller of the children may ask to be picked up. But sometimes when it's time to change them, they'll drop to the floor and flail their legs in a sudden fit/tantrum, or stiffen up and try to pry themselves from someone's grasp/arms.

The smaller children may ask to be picked up. Sometimes, however, when they need to be changed, they’ll suddenly throw themselves to the ground kicking (and screaming), or they’ll arch their backs and try to squirm out of someone’s grasp/arms.