"O menino joga a sopa no chão." Why in previous lessons could we use the article "o" or "a" to be his or her, but here it cannot be "his soup" its only "the soup." It would also make sense for "The boy throws his soup at the floor." Would it need to be "O menino joga a sua sopa no chão." ??
It may seem a bit weird (but no weirder really than butterflies writing books – and I can guarantee you that a lot of children do play with food on the floor) but, outside of Brazil the verb jogar does not mean to throw so it is not wrong if Duo is accepting all kinds of Portuguese (which they often say they are doing).
Also, in English typically the food is thrown at the wall (or, at someone) but, on the floor.