Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Which Previous conference has a Year joined smaller than 1976, and an IHSAA Class of A?

### Inputs:
table_name: table, columns: ['School', 'Location', 'Mascot', 'Enrollment', 'IHSAA Class', '# / County', 'Year joined', 'Previous conference']

### Response:
SELECT Previous conference FROM table WHERE Year joined < 1976 AND IHSAA Class = a