Stay on I-35 south, past the I-44 interchange (north of OKC), for approximately mile. Exit to the west at the 50th Street Exit. The Zoo is on the left about 1 mile from I-35.
Stay on I-35 north, past the I-40 interchange, for approximately 3 miles. Exit to the west at the 50th Street Exit. The Zoo is on the left about 1 mile from I-35.
From I-40 going west proceed north on I-35 for approximately 3 miles. Exit to the west at the 50th Street Exit. The Zoo is on the left about 1 mile from I-35.
From I-40 going east proceed north on I-35 for approximately 3 miles. Exit to the west at the 50th Street Exit. The Zoo is on the left about 1 mile from I-35.
Exit south on Martin Luther King Ave (Eastern Ave), travel south about one mile and turn east on 52nd Street. The zoo is on the right (south).

From Street Atlas v3.0 by Delorme