There are three short vowels in Arabic: Dhammah (above), FatHah (above) and Kasrah (below).
These are related to the three long vowels (which also function as consonants): Waaw, Alif, Yaa'.
Short vowels are usually dropped in formal writing except in religious texts and some literature works (to help with pronunciation of not-so-familiar words). In this course, we'll continue adding all vowels, short and long. If one of the three letters (Waaw, Alif, Yaa') does not have any diacritical markes above or underneath, you can assume it is acting as a long vowel.
Sukuun (the small circle above a consonant) indicates the absence of any vowels and is usually left out if it's final.
We also met a few more items in level I: Shaddah (double consonant), Hamzah, Taa' MarbuuTah, Tanwiin (double Dhammah, double FatHa or double Kasrah), dagger Alif, Alif MaqSuurah, WaSlah, the Laam-Alif combination and Maddah.
If you can't recognize most of these, you'll find it difficult to follow the material in this course. Below is a graphical reminder of what we've just summarized.