Not your conventional see-saw or teeter-totter (as it's more commonly called in the US) I think this must be sprung for safety's sake. Not so much going Up and Down as describing a gentle arc.
See-saw Margery Daw,
Johnny has a new master,
he only earns but a penny a day,
because he can't work any faster . . .
Up and down the city road . . . . pop goes the weasel.
Not the best background even after trying several angles. C'est la vie.