Why should you check your blind spots when changing lanes?

• To see if there's enough room
• To avoid colliding with motorcyclists who may be riding in your blind spot
  Explanation:

  "Always check your blind spots before changing lanes. Motorcyclists can be obscured by other vehicles and may not be visible in your mirrors. Failing to notice them could result in a collision."
• To make sure you don't exceed the speed limit
• To ensure your turn signals are working