Step 1: Make a Key
First, you will need to know what is what on your DNA model. Write "Key" on the top of your poster board/paper. Then, glue or tape on a piece of black licorice. Label it "phosphate groups". Attatch a piece of red licorice and label it "sugar deoxyribose". These two make up the sugar-phosphate backbone of DNA. Take one gummy bear and attatch it to the paper. Label it "adenine". Then, take a different color bear, attatch it, and label it "thymine". Attatch another color and label it guanine, and then attatch another color labeled "cytosine". These are DNA's four bases. Attatch a marshmallow and label it "hydrogen bonds that connect the bases". If you want some extra credit, try adding these facts:
The order of the bases determines the type of organism and its functionality.
DNA's shape is a right-handed double helix.