Halloween STEM Challenges are collaborative, brain-busting work disguised as fun! Ghosts in the Graveyard is from Bone Bridge® STEM Challenges and it's all about pulleys. Students work in partners or groups against a criteria & constraints list to create a ghost transporter that lifts cotton ball “ghosts” from the ground to the top of a pulley. (For younger students, the teacher will set up the pulley; for older students, the teacher will provide materials and students will include the pulley