Halo Effect
Halo Effect is when one good trait about a person makes you think all their other traits are good too.
Think of it this way
A shiny, clean bowl sits on the counter next to a dull, scratched one. You fill both bowls with the same soup. You taste from the shiny bowl first and rate it higher. The bowl's look changes how you judge what is inside it.
Explaining halo effect by grade level
Think about meeting someone with a big smile. You might guess they are smart and kind, just from that smile. But you do not know those things yet. Your brain fills in the blanks based on one good thing it sees.