The phrase "a number of different classes" is correct and usable in written English.
It can be used when referring to multiple distinct categories or types of classes in various contexts, such as education or programming.
Example: "The course offers a number of different classes to cater to students with varying interests and skill levels."
Alternatives: "several distinct classes" or "various types of classes".
Data are shown to illustrate the utility of the system with a number of different classes of protein.
A number of different classes of dirhodium II) catalysts have been found to be broadly effective in this chemistry.
It is most suitable in describing languages (such as the Central and South American languages to which it has mostly been applied) in which a number of different classes can fulfill the same function or in which the same class can fulfill many functions.
Short-oval circuit racing is a world away from the glamour of Formula 1. Race meets consist of a series of events in a number of different classes, from bangers and stock cars to stock rods.
The approach was examined using a series of new natural products reported in the literature in 2008 and belonging to a number of different classes – steroids, alkaloids, terpenes, cembranoids, etc.
Understanding how the average schooling performance of an individual's peers influences the individual's own performance in a setting where students share a number of different classes (e.g. De Giorgi et al. 2010), or where students have some (but not all) common friends (e.g. Bramoullé et al. 2009).
Ga-branch analysis enables the assignment of lineages in a phylogeny to a fixed number of different classes of ω, thus allowing variable selection pressure without a priori specification of particular lineages.
For 5G, a network densification with a high number of different classes of users and data service requirements is expected.
Using a lipid overlay assay, an array of single-lipid species was simultaneously tested for interaction with a protein of interest, thus allowing rapid screening of protein lipid interaction with a large number of different classes of lipids.
Bivariate choropleth maps will be less effective in cases where a large number of different classes are required.
At the beginning, the game let you select from a number of different character classes; you could have gone for Mighty Warrior, Wise Sage, Eagle-Eyed Archer or Dread Warlock.
