Third Grade Pre-existing Abilities, Prior Knowledge, and Prerequisite Skills

One of the third grade Common Core standards (CCSS.Math.Content.3.G.A.1) requires that by the end of the year, third graders “Understand that shapes in different categories (e.g., rhombuses, rectangles, and others) may share attributes (e.g., having four sides), and that the shared attributes can define a larger category (e.g., quadrilaterals). Recognize rhombuses, rectangles, and squares as examples of quadrilaterals, and draw examples of quadrilaterals that do not belong to any of these subcategories.”

To achieve this standard with South Cedar’s third graders, I am planning a polygon unit for them.  One of the lessons toward the end of the unit focuses on octagons.

Here are the skills and abilities needed by the students to be successful in this specific lesson:

·      Know and explain the attributes of a polygon (straight sides, closed shape, 2D)

o   The students will learn this information earlier in the unit when polygons are introduced.  Since children study shapes from a very early age, and kindergarten, first grade, and second grade standards all require students to know the names of qualities of shapes, students will have prior knowledge concerning many shapes like squares, rectangles, triangles, and so on.  Using this prior knowledge, they can apply their understanding that shapes like squares and triangles have straight sides, have no gaps between connecting lines, and are flat.  They already know the qualities of shapes, so in this unit they are just learning the classification term (polygon) and learning which shapes belong in the category and which do not.  

·         Count to determine the name of a polygon based on the number of sides

o   Counting skills and strategies begin in kindergarten, so by third grade students will be able to count with one-to-one correspondence to determine the number of sides on a shape.  This will allow them to determine if the shape is a triangle, quadrilateral, pentagon, etc.  This skill will also allow them to count as they create octagons to make sure they have the correct number of sides.  

·         Use a straightedge to create octagons

o   This skill comes from both art, math, and from practical usage in other fields.  Students have experience connecting two dots with a ruler or edge of a book.  I have watched them all do as much as they created shapes in earlier math lessons.  

·         Open the GeoBoard iPad application and create polygons, including octagons

o   The school received iPads at the beginning of the school year.  At that time, all of the students were given tutorials.  Each student has a chance to use an iPad about every other day, so they keep up on their abilities.  Every student knows how to turn on an iPad, locate a specific app, open the app, and use it.  We introduced the GeoBoard app during a lesson about area and perimeter earlier in the year, so I know that they can successfully use it.