Math book recommendation

This book contains some short and curious puzzles for students who want to use their brain. Always funny and entertaining.
Libro de adivinanzas y problemas matemáticos curiosos y divertidos. Para ayudarte a pensar. Recomendación para todos nuestros alumnos.

Project Noah

Project Noah is a tool to explore and document wildlife and a platform to harness the power of citizen scientists everywhere.
You´d better go to: http://www.projectnoah.org/