Learning goals: Teacher Facing Identify the midline, amplitude, and horizontal translation in trigonometric functions presented graphically and with equations. Predict how changing the value of $k$ in $y=cos(kx)$ changes the graph of the function for whole number values of $k$. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from Alg2.6 Trigonometric Functions, Algebra 2.