Question: what was the purpose of the first earth day event on april 22 1970
[{'answer': 'an environmental teach - in', 'provenance': [{'wikipedia_id': '158548', 'title': 'Earth Day', 'start_paragraph_id': 3, 'start_character': 477, 'end_paragraph_id': 3, 'end_character': 508, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '158548', 'title': 'Earth Day', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 847, 'bleu_score': 0.9863473221773311, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16356453644243282782}, 'section': 'Section::::Abstract.'}]}]