“I’m not smart.”

“I’m not good at math.”

“I wish I could play the piano like her.”

“I’ll never play soccer as well as him.”

“I hate the way my hair looks.”

“I need to lose weight so I can look like her.”

“He’s more popular than I’ll ever be because his parents are rich.”

I have heard phrases like these from my students countless times over the last 20 years of teaching middle schoolers. All of them are indicators of self-concept.