When it comes to fourth- and fifth-grade math, there's often "a tradeoff between 'good teaching' where kids learn stuff and 'good teaching' that kids enjoy," writes Jill Barshay on the Hechinger Report, citing a newly posted working paper.

Researchers found that "teachers who were good at raising test scores tended to receive low student evaluations," while "teachers with great student evaluations tended not to raise test scores all that much"
Teachers whose students earned higher scores didn't spend more time on test prep or "drill and kill," said researchers, who watched hours of taped lessons. Instead, they taught "more cognitively demanding lessons."
That seemed to decrease student engagement, perhaps because they had to work harder.
In my days as an op-ed columnist, I defended Barbie for saying "math is hard." It is hard for many people. But that doesn't mean they can't learn it, if they're willing to work at it.
Only six of 53 teachers raised test scores and received positive evaluations from students, the study found. These teachers tended to use hands-on activities with students working together "using tactile objects to solve problems or play games," writes Barshay.
These doubly “good” teachers had another thing in common: they maintained orderly classrooms that were chock full of routines. . . . “Teachers appeared quite thoughtful and sophisticated in their use of routines to maintain efficiency and order across the classroom,” the researchers wrote. “The time that teachers did spend on student behavior typically involved short redirections that did not interrupt the flow of the lesson.”
These teachers also had a good sense of pacing and understood the limits of children’s attention spans. Some used timers. One teacher used songs to measure time. “The teachers seemed intentional about the amount of time spent on activities,” the researchers noted.
Students who rated their elementary teachers as more engaging "had higher math and reading achievement scores and fewer absences in high school," reports Barshay. "The students who had teachers who were more effective in raising achievement were generally doing better in high school too, but the long-run benefits faded out somewhat."
Math, like many other activities that require effort, is rewarding if you feel that you are achieving mastery, in the sense of gaining a tool that you can use successfully -- whether it is figuring out how much change to expect from a simple purchase or calculating the area of a triangular piece of land where you want to spread compost -- or comparing the price per unit of two different sizes of detergent. If, for any reason, a child is not gaining a sense of mastery during math class, it will be almost impossible for her/him to maintain interest.
Of course math is hard. It's also rewarding and sometimes fun. Cleaning the house isn't fun, either, but you have to do it. The idea that everything in school must be fun and happy and full of rainbows and bunnies is antithetical to learning.