Read about two great programs for free (or discounted) bowling ...
I'm not going to give a lot of commentary about these programs, as I haven't personally taken advantage of them. But I know people who have and it sounds like a great deal. As you will see, the main difference between the two programs are the participating bowling alleys. So you'll probably want to sign up for whichever one has a bowling alley closest to you. Both have a number of bowling alleys in the Portland area (and nationwide).
Important to note that both programs have family/adult passes available. So not free like kids, but pretty good prices (especially if you use it a decent number of times).
Bowl Summer Games: https://bowlsummergames.com/
Kids Bowl Free: http://www.kidsbowlfree.com/
And HERE is a SlickDeals thread discussing the topic.