I believe that Jeter = throwing something away (carelessly), and Lancer = throwing something targeted at some goal. For throwing away trash, use jeter. For throwing something like a spear, use lancer. (By the way: A spear translates in french as une lance. Probably not just a coincidence)
There was a tradition of Yuletide fortune telling in Russia when an unmarried girl would throw her shoe on the road, then the toe of the shoe was believed to point at the direction of her future husband.
Very similar Czech Christmas tradition... The girl turns her back to the door and throws the shoe behind herself. If the tip points to the door, she is to get married the upcoming year.
The first translation of the word "lance" is "spears". Why isn't it accepted in the answer?
Watch out for Duo's drop-down hints. Given the sentence "La fille lance une chaussure", it is clear that "lance" is a verb. What verb? (lancer). Lancer = to throw. http://www.larousse.com/en/dictionaries/french-english/lancer/46054
"Toss" doesn't have the same punch as "throw". In this case, when someone is using shoe, it sounds they really mean to throw it at someone rather than toss it in a trashcan. "Hurl" maybe, but "toss" doesn't feel right :)
There is a lot of overlap, but some slight differences, too. For details, consult your dictionary app:
I got this question translating english to french instead, and it corrected chaussure to soulier. Is there a reason for the differences?
It has to do with the way Duo processes your answer. If you make a gender error, e.g., put "un chaussure" (WRONG) instead of "une chaussure" (RIGHT), it recognizes the error. But instead of telling you the gender of the article is wrong, it will suggest a masculine noun, i.e., "un soulier". It doesn't help reinforce the idea of "chaussure". It tends to confuse the matter when it is simply a gender error. There is nothing we can do to fix that. Sorry.