practice

  1. Write something.
  2. Write something else.
  3. Write something different.
  4. Write something completely different.

conceptual

  1. If you encounter a sonic boom, is this evidence that an aircraft of some sort has just exceeded the speed of sound?

numerical

  1. Which is faster?
    1. Which of these airplanes is moving faster? (Source: NASA)
           
      Photograph of F-18 shock waves   Photograph of T-38 shock waves
      F-18   T-38
           
    2. Which of these bullets is moving faster? (Source: unknown)
           
      Photograph of bullet shock waves   Photograph of bullet shock waves
      bullet 1   bullet 2
           
    3. Rank all four objects in terms of increasing speed.