We spent the first part of the class period learning about the properties of water. Students reviewed the vocabulary of molecule and atom (as in, a molecule of water consists of two atoms of hydrogen and one atom of oxygen). We discussed the difference between covalent bonds and hydrogen bonds, with students learning about electronegativity and partial positive and partial negative charges. We then applied that learning to the study of DNA, with students learning how the DNA bases adenine and thymine align via hydrogen bonding, and similarly with guanine and cytosine. Students then worked in pairs to build an A, T, C, or G molecule, and then found another group with the complementary base to visualize the hydrogen bonding sites. Students then drew out their molecule pairs, labeling the vocabulary terms of molecule, atom, covalent bond, and hydrogen bond. Pictures from the whiteboard are shown below. Students wishing to review the structures can see the nucleotide pairs and hydrogen bonds by clicking here.