A teacher supplied students with a list of verbs in their in...

A teacher supplied students with a list of verbs in their infinitive forms, and asked them to look for the past forms of the indicated verbs (which are regular and irregular ones). He/She oriented learners to observe strutural and spelling similarities and divergencies while accomplishing the task. In order to complete the assignment students would use a cellphone app indicated by the teacher, and also work in pairs. The ability which the activity described specifically seeks to improve is: