My son (10) was freezing last week. He asked me if there was anything he could wear under his jeans to keep his legs warm. He told me he wore his sports under amour under his jeans, and it didn't help! My daughter (12) told him that socks that go over his knees or thick tights could do the trick. He wants to give both long socks and tights a try. Where can I find boys socks that go over his knees, and should he wear tights under his jeans? It's only going to get even colder! Thanks!