ei lekse · homework
Feminine (ei)
Indefinite singular
ei lekse
Definite singular
leksa
Indefinite plural
lekser
Definite plural
leksene
Feminine nouns (ei) can always be written with en as well: ei bok, boka or en bok, boken. Both are correct Bokmål.
How to guess the gender Nouns: gender and articles