Here's why:
* Short vowel sounds are typically quick and sharp. They are often found in words with one syllable, like "cat," "dog," and "hot."
* Long vowel sounds are typically drawn out and have a more open mouth position. They are often found in words with two syllables, like "gate," "cone," and "bike."
The vowel sound in "robot" is a quick and sharp "o" sound, similar to the "o" in "hot" or "cot." This makes it a short vowel sound.