Students tend to want quick answers. Most haven't discovered the joy of 'questioning and connections.' It's very easy to take the quick-fix and just provide them with a solid answer, without any self-discovery integrated. We can say we "taught" the standard even though we haven't necessarily helped them comprehend the content on a deeper level. It's better to be committed to changing the expectation and require self-discovery within the standard.
As teachers, we have a a pathway for teaching content and sometimes, specific standards, like functions, may require more time and differentiation than the guide or time dictates. Students don't always grasp the significance of a mathematical concept being introduced until they gain a greater perspective of it's purpose. Our classroom time-frame and the student's life experiences may not provide a best-case scenario for understanding. We need creative ways of expanding their understanding and real-world perspective (videos, hands-on, etc).
Students also tend to be afraid or negative when real-world word problems are introduced. Helping them to find word clues and connecting those to real-world situations is key in getting them to move toward successfully processing those problems confidently.