On the opening words of our Parsha, "Speak (Emor) to the priests," Rashi comments: "Speak ... to warn the adults about [educating] the children."
At the literal level, the verse is speaking of the specific responsibility of adult priests to educate their children about the priestly duty to remain ritually pure. However, in a broader sense, since this is the opening of a Parsha which contains guidance for Jews in general, our verse could be understood as a warning to all parents about the importance of educating their children.
In this case, we are not speaking about the basic necessity of education that is required to raise up the next generation, since such a fundamental principle would surely have been given soon after the giving of the Torah, rather than here, near the end of the Book of Vayikra.
Rather, the opening of our Parsha is hinting to a more advanced approach to education, which becomes relevant after a child has already been taught the basic principles of right and wrong ..
The precise nature of this advanced approach is highlighted by another important concept in our Parsha: the counting of the Omer (23:15-16). Not only is this a mitzvah which is recorded in our Parsha, it is a precept that we actually observe at the same time as reading the Parsha, since Parshas Emor is always read during the Jewish month of lyar, during which the Omer is counted every day.
Chasidic thought explains that Counting the Omer is, in fact, an advanced form of education, where a person progressively advances to higher levels of spiritual achievement as he refines different aspects of his personality step by step, on a daily basis.
The lesson here is: "to warn (להזהיר) the adults about [educating] the children." The Hebrew term להזהיר is a derivative of the word זוהר, meaning "light." So' Rashi is teaching us that education is a neverending process that needs to grow constantly on a daily basis, bringing many positive qualities to our children so that they literally shine with light.
(Based on Sichas Shabbos Parshas Emor, 5750)