Harry was never helped with his homework as a kid. So he always struggled with school, never could read as fast as other kids. He wasn't able to see in the dark cupboard under the stairs so there was no hope of doing extra work there. Usually words tended to move around the page. Although no one had asked to care why he struggled to read. Other kids thought it was funny to laugh at him about it though.

"Mr Potter can you read the next paragraph out loud" Said Snape.
"I'd rather not sir" young Harry replied quietly fiddling with his hands.
"Let me rephrase that. Read the next paragraph" He grounded.

Harry looked at Hermione who smiled in encouragement.
He cleared his throat and started.
"Uh one of the many plants that have multiple uses are mandr..Mandrake? They have numbernous."
"Numerous" Hermione whispered beside him.
"Numerous attributes" Harry quickly fixed.
"They are therefore the most poly-mor...uh plants to be used in potions."

"Granger take over" Snape ordered.
Harry flushed and he looked down at his feet. Everyone somehow thought he was great but he supposed he was much less than great.