Why Are Snowflakes Six-Sided?

Open the investigation with the surprising fact: despite infinite variety, every snowflake shares six-fold symmetry.

• Snowflakes come in countless designs
• All natural snowflakes have six arms
• The driving question: why six?

Commit to one cause before the science reveals it.

• Choose the most likely reason
• Lock in a hypothesis to test

See how a single water molecule bonds to four neighbors and how those bonds pull the structure into a hexagon.

• Drag the oxygen and hydrogen atoms
• Watch bonds form to four neighbors
• Notice the angles that appear

Reveal the hexagonal crystal lattice, the invisible blueprint every snowflake follows.

• Each water molecule bonds to four others
• Bonds angle at roughly 109.5 degrees
• The bonds stack into repeating hexagons
• All snowflake branches follow this lattice

Explain how the hexagonal lattice forces every growing branch into six-fold symmetry.

• Ice grows by adding molecules to the lattice
• Corners of the hexagon grow fastest
• Branches sprout at 60-degree intervals
• Six identical arms emerge from one shared pattern

Test the explanation by changing the bond angle and watching the resulting crystal shape change.

• Adjust the bond angle slider
• See how the lattice geometry responds
• Confirm that six-fold symmetry depends on this angle

Show that other shapes are not stable for water, so only the hexagon survives.

• Three or four arms would break hydrogen bonding
• Eight or twelve arms would not match water's bond geometry
• Only six arms satisfy the bond angles

Close the investigation by directly answering the driving question.

• Water molecules bond to four neighbors
• Those bonds form a hexagonal lattice
• The lattice forces every snowflake to grow six arms
• Six sides is the shape of water freezing