Participles are a verb form used in passive sentences and to form perfect and progressive aspect. There are two participles in English, the present participle (-ing) and the past participle (-ed).

Example
'I'm leaving', 'we wanted to go', 'a very boring film' and 'they were really excited by the news' are examples of participle forms.

In the classroom
Areas of language involving participles include present continuous, past simple and perfect forms, passives and adjective formation. Learners sometimes have considerable difficulties understanding the differences between adjective forms such as 'exciting' and 'excited'.

Further links:
https://www.teachingenglish.org.uk/article/left-handers
https://www.teachingenglish.org.uk/article/have-you-ever