IMHO this is fundamentally unethical. The purpose of education - again, IMHO - is to equip children with the skills and knowledge they need to be successful in the wider world. Advertising has no place in this model.
The example given by gumby is particularly insidious. I could make the argument for including products that the children will be familiar with to make maths problems seem more applicable to the real world. However, knowing that the "best-selling packaged cookie in the world is the Oreo cookie" does nothing to enhance the child's mathematical ability.
The Merchants of Venus by Frederick Pohl is a satirical SF story about the potential perils of runaway capitalism. I could see school districts experiencing rivalry depending on whether they are a "Coke school" or a "Pepsi school". The last thing school systems need is yet another superficial basis for tribalism and rivalry.
There is one potential benefit that I can see. Advertisers would presumably pay money to schools for the privilege of advertising to such a malleable, captive audience. If this money were to be used to enhance the quality of education at the school, could it outweigh the damage caused by advertising to children? I'm not sure, but I doubt it.