Younger students can make a paper model of the origami double helix structure. Draw a ladder on paper with double lines for the rungs and the edges. Cut out the spaces in between the rungs forming a flat double helix. Gently twist the shape to coil the edges and produce the familiar DNA double helix. Older children can color in the rungs of the ladder to represent the pairs of chemical bases before they cut out the ladder shape.
Students produce edible models of DNA, highlighting its double helix structure and the arrangement of the bases. Imagining a flat ladder shape, students cut short lengths of red and black licorice and string them on thread to form two strands, alternating the colors. Pairing up one each of two colors of marshmallows on a toothpick gives one pair of bases, and another two colors gives the second pair. Arrange the toothpicks across the licorice strands, pushing them into the licorice and alternating the pairs of colors and flipping every second toothpick for each color pair. A gentle twist of the licorice model gives an edible DNA model.
Making a jewelry model of DNA is similar to the candy model but the construction is more detailed and involved. Using six colors of tubular beads, wire and needle-nose pliers, students create long-lasting and wearable DNA models. Flat DNA models make good bracelets, necklaces or bookmarks, while the coiled models create interesting keyrings and earrings. String two colors of the beads together on jeweler's wire for the sides of the helix, and tie wire with the colors for the chemical bases to the strands in between the side beads.
This DNA model explores DNA coding rather than its structure. Each of the 20 amino acids has been assigned a letter of the alphabet, and each amino acid is associated with one or more triplets of DNA bases. Students use colored building blocks to create their names written as DNA messages, using predetermined colors for each of the four chemical bases. To decode the message, students divide the string of blocks into threes, decide which chemical bases are represented and look up the sequence in a table to determine each letter. Older students can encode a message in this way in their DNA jewelry. Some creativity in the messages is required as there is no code for B, J, O, U, X and Z.