PS 321 in Park Slope is having its annual Winter Carnival this Saturday (3/8). There will be games, prizes, face painting, food and entertainment. There are supposed to be pony rides if the weather is good, but the latter is not looking very promising. there is also rummage sale with children’s clothing, games, toys, books and DVDs. There will be a raffle with money being used to buy math books that have been cut from the education budget. Among the prizes are Wii games, an iPod Nano and an American Girl Doll. Raffle tickets are 2 for $5. PS 321 is on Seventh Avenue between First and Second Streets in Park Slope.