What saying does Holling quote Shakespeare on before Mrs. Baker grades his 150 question test?

Holling Hoodhood quotes a small bit of text from Shakespeare's play The Tempest.  The line that he quotes is the following line:

“The quality of mercy is not strained”

To be really specific, Holling does not say the line before Mrs. Baker grades his 150 question test.  He says the line during Mrs. Baker's grading.  Mrs. Baker begins grading the test, and marks the first four questions wrong.  She makes the comment that Holling is...

Holling Hoodhood quotes a small bit of text from Shakespeare's play The Tempest.  The line that he quotes is the following line:

“The quality of mercy is not strained”

To be really specific, Holling does not say the line before Mrs. Baker grades his 150 question test.  He says the line during Mrs. Baker's grading.  Mrs. Baker begins grading the test, and marks the first four questions wrong.  She makes the comment that Holling is not having such a good start.  Holling responds with the above quote.  The response pleasantly surprises Mrs. Baker, and she smiles in spite of herself.  Holling can hardly believe it, which is why he points out to his readers the fact that she did indeed smile.  He even tells his readers that it was almost a real smile.  Not a fake teacher smile.  The exchange is important, because it is one of the first times that Holling sees there might be a possible chink in Mrs. Baker's tough exterior.  It's also one of the first times that Mrs. Baker begins to suspect that Holling has a natural affinity toward Shakespeare.