My ds (almost 17 months) has been practicing his throwing skills too! And also his artistic talents of smearing all his food on his tray with big sweeping motions. We give him two chances. We warn him, "we don't throw food at the table. Food is for eating, not throwing." After the second time, we take his tray away and repeat ourselves. Then, after a couple of minutes, we give the tray back. If it happens again, then he is done with dinner. BTW...he also understands "all done" most times so we ask him that, too. Then, later, if he's hungry I'll alow him to have some fruit, crackers, cheese or a bar. I'm hoping that it will work and I'm getting better at noticing when he is not interested in something and I intervene before he throws by asking him to give it to mommy and if he does I praise him. I'll also offer a food and if he starts to get the look, I'll remove it. Good luck! I'm eager to hear what works for others, too!