7.1 concept learning 7.1.1 concept A concept is a category under which specific elements may be grouped.e.g. a red ball, a red pencil, and a red chair are all instances of the simple concept “red”. An “even number” is defined as any integer(整数) that is divisible by two without a remainder, and that an “odd number” is one that is not evenly(均匀地) divisible by two