Juan Daniel and his friends can hardly wait for the neighborhood fútbol (or soccer) championship. However, when Juan Daniel hurts his arm during the game, he ends up watching most of it from the sideline. While there, Juan Daniel finds a frog hopping around the endge of the dusty field, far from its natural habitat. The frog inspires Juan Daniel to overcome his injury and lead his team to victory!

After the game, Juan Daniel realizes that the frog is in need of help. The frog's skin is a membrane that needs to be kept moist in order for the frog to suvive. With a little help from a bioengineer visiting Juan Daniel's village in El Salvador, he works to create a model membrane to save his fútbol frog.

Readers are invited to design a model membrane. With some creativity and knowledge of the engineering design process, everyone can engineer!