BasicStudents matched to this level have a partial mastery of prerequisite knowledge and skills fundamental for proficient work.
At Grade (Proficient)Students matched to this level have demonstrated competency over challenging subject matter, including subject matter knowledge, application of such knowledge to real-world situations, and analytical skills appropriate to subject matter.
AdvancedStudents matched to this level are ready for material that requires superior performance and mastery.
Invertebrates are a large group of the animal kingdom that have no backbone and share other unique characteristics that set them apart. Watch this educational video from About.com to learn more about invertebrates.
Courtesy of about.com