Quick check
Tap a Spanish word, then its English partner
Possessives agree with the thing owned, not the owner
English picks the possessive by the owner: his sister, her sister. Spanish uses su for both, and changes only for how many things are owned.
mi / mis · tu / tus · su / sus · nuestro / nuestra / nuestros / nuestras · vuestro / vuestra / vuestros / vuestras · su / sus
Su hijo can be his son, her son, their son or your son (formal). Context decides.
The trap: sus hermanas is plural because there are several sisters, not because there are several owners.
su is not ella, and tu is not tú
Your class notes have this pair the wrong way round, so read it once carefully.
su / sus is the possessive adjective: her, his, their. It sits in front of a noun. Su marido = her husband.
ella is the subject pronoun: she. It stands where the subject goes. Ella va a Londres.
The trap: tu with no accent means "your"; tu with an accent means "you". Tu hija is your daughter; tu eres is you are.
ir a, and the a never disappears
ir is voy, vas, va, vamos, vais, van, and it always takes a before a destination or another verb.
Voy a Menorca. Vamos a estudiar espanol.
The trap: Voy la biblioteca and Van estudiar en casa are both wrong options in the class MCQ set. The a is not optional. And a + el contracts: voy al monte.