The rate constant depends on things like activation energy and orientation of individual molecules, but the overall rate in moles per liter per second also depends on how many molecules per liter there are. For the common First Order Reaction

Rate (mol/L·s) = Rate Constant (/s) x Concentration (mol/L)

If the concentration doubles, the rate doubles. Other courses deal with how concentrations change over time. In addition to chemistry, this rate law is used in biological populations and radioactive decay, where terms like doubling time and half-life are used.