At ultracold temperatures, we can prepare reactants in well-defined quantum states. Doing so allows us to study the quantum dynamics of individual reaction channels. I will present our work on ultracold chemistry using triplet NaLi molecules. First, we discovered strongly spin dependent chemistry. For certain reactions, the reaction rate changes by a factor of 100 when you change the spin state of a reactant. For one specific channel, quantum coherence in the chemical collision allows the reaction rate can be tuned by a factor of 1000 using an external magnetic field. Reactions involving triplet NaLi brought to light surprising properties of quantum collisions that contradicted the best theories at the time. After giving a picture of just how much we can learn about quantum collisions and chemical dynamics with ultracold techniques, and how this knowledge connects to industrially important chemical reactions, I will discuss our current efforts toward quantum simulation, precision measurement, and quantum computing with ultracold molecules.