Here's why:
* Short vowel sounds are single, distinct sounds like the "a" in "cat" or the "i" in "pin".
* Skipping has the vowel sound "i" followed by the vowel sound "ɪ", creating a gliding effect. This combined sound is what makes it a diphthong.
Think of it like this: you start with the "i" sound in "see" and then slide down to the "ɪ" sound in "bit".
So, while skipping involves a vowel sound, it's not a short vowel but a diphthong.