Some free PDF's

www.naturedetectives.org.uk has some great free PDFs to download aimed at kids or even 'noobs' they are worth a look. Print some off next time you have kids with you on a trip to the woods.
The whole site is great for kids who have an interest in nature.
Highly recommended.

Grouped by season, these ID sheets provide a simple aid to getting to know common trees, flowers, butterflies, birds and insects. The sheets are designed for beginners, but some are also helpful for more advanced identification needs, for instance distinguishing between winter twigs.