Some studies indicate that grouping can damage students’ self-esteem by consigning them to lower-tier groups; others suggest that it produces the opposite effect by ensuring that more advanced students do not make their less advanced peers feel inadequate. Some studies conclude that grouping improves test scores in students of all levels, others that it helps high-achieving students while harming low-achieving ones, and still others say that it has little effect. (NY Times)
Would it really be that hard to add in links to the actual studies here? Newspapers are digital entities now as much as they are paper ones. They need to learn how to link their syntheses with the knowledge they've drawn upon. Satisfy one reader's curiosity and you've made that reader more likely to become a repeat customer.