Jamal wants to know how fast his skateboard can roll down the ramp in front of his school. So, Jamal places the back of the skateboard even with the top of the ramp and times how long it takes before the front of the skateboard reaches the end of the ramp. After he records the time, he performs this procedure again four more times and calculates the average time. During his experiment, Jamal demonstrates ______.
renovation
regeneration
replication
repetition