Help with sentences

I have a small Spanish project and I was wondering if my sentences are correct.

1. Mi primera palabra fue bola (My first word was "ball")
2. Mi primer día de jardín de infantes estuvo bien (My first day of kindergarten was fine)
3. Mi clase favorita era la de ciencias (My favorite class was science)
4. Caminé por primera vez antes de cumplir un año (I walked first before I was one year old)

For my Highschool class, so it's really basic and I was wondering if there's a better way to write anything; or if it's okay