I did it on a spur of a moment but our children loved this!
When I saw the book, “spot a bug”, on sale for a couple of euros, I bought it hoping we’d get some use out of it when camping in the summer. I don’t know too much about bugs because…ewww! But kids are curious, hey ask constantly, and I think they should explore no matter what I think.
Our children and their friends have been out looking for bugs (and leafs and sticks…) with magnifying glasses for many days now!
The book is simple but informative. It encourages also with stickers: every time you find a bug, you get to look up the equivalent sticker in the book. To recognise it among the many bug stickers you have to look carefully, compare colours and count the number of legs etc.
What a great way to learn more about the nature and what a great purchase!
However, I don’t think one have to have such a book even though it is well made. One could easily do a similar thing by drawing up a chart of (could be flowers or mushrooms too ), get a lexicon from the library and regular stickers to mark the ones spotted.
Free But Fun 
What a way to let them learn and be entertained!!
Wonderful, fun learning book.