HGS Polyhedron Molecular Models (1 Å = 2.5 cm) are very useful for students taking undergraduate chemistry courses such as general chemistry, organic chemistry, inorganic chemistry, crystallography, etc. In these models, atoms are represented by polyhedrons having holes corresponding to the exact bond angles. Sticks of different bond length and colors are provided. Students can easily assemble molecular models by considering orbital hybridization of atoms, e.g., sp³, sp², and sp, and bond length. The chair, boat, or ring inversion of cyclohexane can be readily performed. P-atomic orbital plates are also useful for students to understand molecular orbital theory and applications such as the Woodward-Hoffmann rules.