Write a paragraph using the preterite & the imperfect and tell about:

¿Cuál era tu pasatiempo favorito cuando tenias 12 años? 5-6 frases completas

Here is the paragraph I wrote:
Mi pasatiempo favorita cuando tenía 12 años era leer libros. Me encantaba leer todos los libros. Pero la fantasía y la libros ciencia ficción era mi favorito. Pasé la mayor parte de mi tiempo libre en la biblioteca. Cuando mis padres me compraron un Kindle para mi cumpleaños yo estaba muy contenta!

I am not sure whether I used the imperfect and preterite correctly. Also did I use the correct feminine forms?

I'll send this to Sra.

Always check to be sure any adjective has the same number (singular/plural) and gender (masculine/feminine) as the noun modified. Because pasatiempo is masculine singular, the adjective must be favorito.

Again, la does not match libros = los libros de ciencia ficción. The subject is plural, so the verb must be also = eran mis favoritos. (los libros y la fantasía)

Here is a quick review of when to use the Preterit and/or the Imperfect.
The Preterit signifies some that DID happen and is over and done with. the usual English translation is either did... or ...ed. (did study/studied)

The Imperfect signifies something that WAS happening, or USED TO happen. It "paints" the background and has no ending that you know of. (was/were studying/used to study)

The problem arises when the translation is "studied" because you need to picture if it was over and done with OR was ongoing.

I'll flag this and come back later to see if you have further questions.

Sra

Your paragraph is almost perfect! You used both the preterite and the imperfect tenses correctly, and your use of feminine forms is also correct. Just a couple of minor corrections:

1. In the first sentence, it should be "Mi pasatiempo favorito" instead of "Mi pasatiempo favorita" since "pasatiempo" is masculine.

2. In the third sentence, it should be "pero la fantasía y los libros de ciencia ficción eran mis favoritos" instead of "pero la fantasía y la libros ciencia ficción era mi favorito" to match the plural form of "favoritos."

Other than these small corrections, your paragraph is perfect! Well done!