I got to spend a solid 20 minutes with my middle son working on a maths concept he was struggling to understand. He was trying to read a graph, & it took a while for him to grasp that the scale went up in increments of 5. We ended up with the LEGO bricks out and he grappled with the problem for a while before the penny seemed to drop. I explained that the increments of scales differ so you have to work out in each case what you are being shown. My son then went to the kitchen and took out a measuring jug he has used in his cooking. "It's like on here," he said, "this goes up in 50 ml, so if I pour milk up to here, that will be 250ml." (He indicated between the 200 and 300 ml marks.)
This showed me, not only that he had grasped what I was saying, but that he was able then to apply that knowledge to another context. It was a good moment! Without that 1:1 input at school, he might have failed to grasp this concept and, because of the pressure on teachers to get through the curriculum, would probably have been moved on with a gap in the foundation of his knowledge.