A representation of DNA, like any molecular model, cannot accurately capture every detail of the atoms and bonds involved. Instead, a didactically useful DNA model should represent essential elements of DNA's two-dimensional and three-dimensional structure.
Most 3D DNA models use color-coded elements to illustrate the four different types of nucleotides. Match the four colors consistently into two pairs, where each pair forms the rung of a ladder-like 2D structure. Twist the supports of the ladder to illustrate the archetypal helix shape of DNA. You may create a model with this level of complexity using different materials, from polystyrene foam balls to licorice sticks.
Create a simple DNA model using polystyrene foam balls and toothpicks. Divide the balls into six different groups and paint each group a different color. Four colors will represent the nucleotides of DNA, while the other two will stand for the sugar and phosphates that form the backbone of each strand.
Assemble the colored balls around a wooden or metal laboratory stand using the toothpicks. Work carefully, matching each nucleotide color with one other color, while alternating the sugar and phosphate colors in the backbone. Angle the toothpicks consistently so the molecule spirals around the stand as it grows.
A large DNA model teaches kids about biology while serving as an educational and attractive classroom centerpiece. Trace patterns for each molecule onto large sheets of foam board and cut them out. Each "rung" of the DNA ladder will require a pentagon deoxyribose, a smaller, circular phosphate group and two rectangular nucleotides. Color each component with paint or markers.
Assemble the DNA model by stringing the components of each rung onto a metal or wooden bar. Connect the rungs with string or cord, attaching the deoxyribose and phosphates to the outside. Hang the model from ceiling hooks, twisting it gently as it descends before attaching it to the floor.
For a creative and delicious twist on a DNA model, make DNA out of colored marshmallows or gummy candies. Sort the candies into four colors, each representing a nucleotide. Impale pairs of candies with toothpicks to form the rungs. Stick the ends of the toothpicks into a licorice backbone and give the entire molecule a twist. Before consuming the DNA, be sure to disassemble completely and remove all toothpicks.