It's Halloween time and Sid and his friends have dressed up in the spookiest and scariest costumes possible. Sid is a bat with big fangs.May is a spooky black cat. Gabriela is a furry, yucky spider. And Gerald is a super spooky skeleton that goes boo! Susie (dressed as a silly mad scientist) loves their costumes, and helps the kids discover that Halloween can be spooky and scientific! The kids investigate how bats are helpful creatures that catch mosquitoes, spiders are expert engineer web builders, cats are leaping aerial acrobats, and skeletons help hold up our body frames! At the Halloween party, the kids also investigate how to make icky, gooey green slime. Susie then ends the day with a special "Halloween Parade" song so the kids can march around and show off their spooky and scientific costumes!