Next time you visit your local science museum or zoo be sure to ask about their annual pass rates. As my children have grown and we now pay the adult rate for their admission, it has often become more economical if we purchase a season pass; which normally pays for itself by the second visit. If your local science museum is in the ASTC passport program, you will be able to receive free general admission at over 300 science centers worldwide. If you do a bit of research, you may find a science museum that offers reciprocal benefits in both the Association of Science-Technology Centers (ASTC) and the American Zoological Association (AZA) such as Boonshoft Museum of Discovery in Dayton, Ohio. They offer family memberships beginning at $69 and if you choose to purchase an Adventurer Membership for $100, you will also receive reciprocal benefits to the Association of Children's Museums (ACM).
If you purchase your membership at a zoo, the zoo you bought the pass at will allow free admission every time you visit their zoo, and normally, 1/2 off to all other zoo's you may visit over the course of a year. Be sure to purchase your pass at the zoo you will visit most frequently!
Our family has found the reciprocal benefits to be a huge bargain while traveling.
****Before purchasing your membership, look over the above websites so you can see if the reciprocal benefits will be a good fit for your family. Many of the museums offer limits on the number of children permitted, so large families may not be able to gain free admission to all attractions, but this should still reduce admission fees.