The phrase "activities in this book" refers to the things you can do or tasks you can complete that are mentioned or provided in the book. Full definition
If you are frustrated or worried about your emotional child, the hands - on activities in this book — including child - friendly mindfulness practices — can help. (newharbinger.com)
There are 59 pages of activities in the book we have, so the book alone has plenty of learning opportunities. (momsfavoritestuff.com)
In fact, some of my favorite activities in the book involved just a laundry basket and rolled up socks! (mamanista.com)