Apologia Chemistry: Periodicity or Periodic Trends

We are mopping up general chemistry lessons, one of which is Periodic Trends (Module 8 Molecular Structure): metallic character, nonmetallic character, ionic radius, atomic radius, electron affinity, electronegativity, first ionization energy, density, boiling point, melting point, and valency.  I wrote these and assigned each kid a different one.  The kids may use a variety of materials to represent their assigned trend: toothpicks, straws, color, etc.  They must define the trend and explain the pattern across the main group elements of the periodic table.