  This paper discusses an instructional strategy which explores eventual
similarities and/or analogies between familiar problems and more sophisticated
systems. In this context, the Atwood's machine problem is used to introduce
students to more complex problems involving ropes and chains. The methodology
proposed helps students to develop the ability needed to apply relevant
concepts in situations not previously encountered. The pedagogical advantages
are relevant for both secondary and high school students, showing that, through
adequate examples, the question of the validity of Newton's second law may be
introduced to even beginning students.
