Answer:
6a. The plastic shopping bag is opaque, meaning light is not able to pass through it.
6b. Yes, the plastic shopping bag cast a shadow.
6c. The plastic shopping bag casts a lighter shadow than the cardboard shapes because the material of the plastic bag is less dense and does not absorb as much light, resulting in a lighter shadow.
6d. Yes, the clear plastic shape cast a shadow.
6e. The cardboard and the plastic shopping bag cast shadows because they are both opaque materials which block out light and prevent it from passing through. The clear plastic does not cast a shadow because it is transparent, meaning it allows light to pass through it.