人教版初中物理第一册有一节实验课:“测平均速度”,实验方法是:让小车从斜面上滑下,用停表测出小车通过某段路程所用的时间,用刻度尺测出这段路程,计算出平均速度。此实验难点在于运动时间不易测准,尽管教材中已要求:“在正式测量以前,应该先练习几次,熟练以后会测得更准。”? There is an experimental lesson in the first edition of Physics Education Junior Middle School Physics: “measuring the average speed”. The experimental method is: let the trolley slide down the slope, use the stopwatch to measure the time spent by the trolley through a certain distance, and use the scale to measure Calculate the average speed during this period. The difficulty of this experiment is that the exercise time is not easy to measure, even though the textbook already requires: “Before the formal measurement, you should practice a few times, and later you will be more accurate when you are skilled.”