As the S&C editor notes, most of us have had struggled with hard-to-teach concepts. But as one article states, Hard to Teach Does Not Mean Impossible if the classroom is an environment in which students feel comfortable questioning and sharing their thinking, if preconceptions or misconceptions that might affect learning are identified, and if connections are made with other subject areas.  (Talking About Shadows describes this “friendly talk.”)
The featured articles in this issue  have suggestions for addressing hard-to-teach concepts with planned and purposeful learning activities, including identifying misconceptions, rubrics, lesson plans, and examples of student work. (It may be a coincidence, but it seems that most focus on physical science concepts. Hmm.) NSTA’s SciLinks has collections of vetted websites with background information on the concepts and additional teacher resources:

• Changes Matter!  [SciLinks: Physical/Chemical Changes, Law of Conservation of Matter]
• Experiencing Friction in First Grade [SciLinks: Friction]
• Talking About Shadows, Modeling Light and Shadows  [SciLinks: The Sun]
• How Does Force Affect Motion? [SciLinks: Forces and Motion (K-4), Forces and Motion (5-8), Friction, Force of Gravity, Gravity]
• May the Magnetic Force Be With You [SciLinks: Magnets, Magnetism, Magnetic Fields]
• Shining Light on Misconceptions [SciLinks: Light, Light and Color]
• Energy Makes Things Happen [SciLinks: Energy, Sources of Energy, Energy Transformations, Winds]
• Does Technology Evolve? [SciLinks: Technology and Society, Inventions/Inventors]
• More Is Less [SciLinks: Parts of a Plant, Plant Growth]
• The Spider Files [SciLinks: Arthropods]
• Big Ideas for Little People [SciLinks: Biological Evolution, Vertebrate Evolution]

Many of these articles have extensive resources to share, so check out the Connections for this issue (October 2012). Even if the article does not quite fit with your lesson agenda, there are ideas for handouts, background information sheets, data sheets, rubrics, and other resources.