This lesson is for gerunds that do not follow the direct -ando or -iendo rule. Learn the changed gerund together with estar.
Which verbs change the stem
An -ir verb that changes its stem in the present changes it in the gerund as well: e → i and o → u — pedir → pidiendo, sentir → sintiendo, dormir → durmiendo. An -ar or -er verb keeps its stem: pensar → pensando, volver → volviendo. poder → pudiendo is the exception.
i → y
Where the stem ends in a vowel, -iendo becomes -yendo: leer → leyendo, oír → oyendo, construir → construyendo. ir → yendo has a form of its own.