Place carrots in a saucepan. Add water to cover and bring to a boil. Cover, reduce heat, and simmer 12 minutes or until crisp-tender; drain. Combine pineapple, cornstarch, and ginger in a medium saucepan; bring to a boil. Reduce heat to low, and cook, stirring constantly, until thickened. Add carrots, and cook 1 minute or until thoroughly heated, stirring occasionally.