Sokka matched her pace in such a way that Toph would hopefully not have to hurry or slow down. The little girl who once hated having anybody help her-- it was kind of an honor, right, that she didn't mind it from him. Least he could do was make it painless as possible, and considering that Katara absolutely did not need him for this kind of thing, no matter how hard he tried to keep her out of trouble, well. It was kinda cute, and a good way to exercise his dormant big brother feelings.

"Had to do something while Katara and Aang were learning waterbending, right? There's an incline coming in three steps."