I have been taking my kids to OMSI for years. We have a yearly membership, and it totally pays for itself in a few visits. My boys love all the different science exhibits and have so much fun they actually forget they are learning.
The main hall has an exhibit thta changes every so often, so it really keeps things new and exciting. This last week, we went to OMSI and for the first time, my 8 year old went into the chemistry lab, where after donning goggles, he was able to perform several chemical experiments that were set up and ready to go. The OMSI staff and volunteers were on hand to offer help and explanation. We had a wonderful time.