All children should learn how to make their voices heard. But grading them on class participation may not be the answer.
Jessica Lahey, author of the piece "Introverted Kids Need to Learn to Speak Up at School," is a teacher who obviously cares deeply for her students. She's absolutely right that reticent children need to be sensitively encouraged to push through their fears so they can make their voices heard when they have something to say, and so they can face the world with confidence and joy.
As others have pointed out in the comments, however, her article is primarily about shy children who fear social judgment, not introverts who simply prefer quieter environments and think before speaking. And grading shy kids based on class participation may not be the best way to help them.
Here are some alternative ideas for helping shy children:
1) Use the "Think, Pair, Share" technique. The teacher poses a question to the class and asks students to first reflect on or write down their answer, and then share it with a peer. Sometimes a shy student can find confidence through the encouragement of a single peer before sharing his idea with the larger classroom.
2) Wait before calling on students. After posing a question to the class, the teacher waits five or ten seconds before calling on students for an answer. This gives reflective kids a chance to think and shy ones time to gather their courage.