In Montessori, every aspect of the curriculum is hands-on--even grammar and sentence analysis. Dr. Montessori assigned a symbol for each part of speech. The noun, being the most concrete of all parts, was assigned a black triangle. This was deliberate on her part as the triangle is an incredibly secure support structure and is often used in the design of buildings. The verb, on the other hand, was assigned a red circle (or sphere) to recognize that verbs are often actions or movements. The following grammar chart shows the basic parts of speech, their definition, and examples for the students to use in symbolizing their work.