Math lessons and more. 
Math gets to be the subject students fear the most, wish they could learn better more than most, and gets to be the one largely suffocated by systemic constraints and confused pedagogies.
People always discuss math being real world, but it is not until it is and that can happen anythime, particularly, the classroom. Calculating a hypothetical train problem is not real world to anyone but figuring out the numbers and systems to make some cool art can be. When the goal is a thing worth trying for, students are more intrinsically motivated to achieve. Maths have a reason and, most importantly, problem solving plays a role in all things.