The phrase "a significant number of classes" is correct and usable in written English.
It can be used when referring to a large quantity of classes in a particular context, such as education or training programs.
Example: "The university offers a significant number of classes in various disciplines to cater to diverse student interests."
Alternatives: "a considerable amount of classes" or "a large number of classes".
For example, has he missed a significant number of classes?
We can observe that the resolver package contains a significant number of classes with bugs.
In the first place, 5 male and 5 female pupils were measured in a significant number of classes instead of the 4 originally planned.
Several gene classes (42 clusters) were identified that had highly significant enrichment P-value scores (less than 0.05; Table S13), as well as a significant number of classes with higher P-values but nonetheless informative regarding pathway analysis.
Others interviewed said a significant number of working-class and middle-class families had left for the southern states or northern New England, where the wages are low, but so are the housing costs.
However, the size and organization of MHC class I encoding regions are considerably variable and the rat possesses a significant number of MHC class Ib genes for which no human homologues exist [15].
A significant number of upper class vehicle suspensions is either equipped with continuously variable dampers or low bandwidth actuators.
I have no doubt that a significant number of middle-class people, if offered merchandise like a TV set and told that it was cheap because it had "fallen off a truck," would fail the integrity test.
A significant number of the class periods are devoted to what are called group active engagements (GAEs).
In 2015, the Labour Party, which was pro-E.U., lost a significant number of its working-class voters to the U.K. Independence Party, which held anti-E.U. and anti-immigrant positions.
These experiences inspired a significant number of white middle-class parents to opt out of the standardized medicated hospital birth beginning in the 1970s.
