Mathematical Emphasis
Investigation 1—Composing and Decomposing Shapes

• Sorting, describing, and identifying shapes by various attributes
• Composing and decomposing two and three-dimensional shapes
• Describing spatial and numerical relationships found among shapes

Investigation 2—What is a Rectangle?

• Identifying triangles and rectangles based on the number of sides, the number of corners, and the number of square corners
• Visualizing, constructing, and drawing rectangular arrays
• Using numbers to compare rectangular arrays

Tips For Helping At Home
Questions To Ask:

• What is the problem about? Tell me in your own words.
• What did you do in class to get started?
• Can you make a drawing (model) to help you figure out the problem?
• What have you already tried? What steps did you take?
• What do you need to do next?
• Can you show it in a different way?
• How did you get your answer?

Helping At Home

• Look at different shapes in the environment. Where do you see rectangles and squares? Are there some shapes within other shapes, such as panes in a window?
• Look for arrays (rectangles made of squares)—for example, in floor tiles, calendars, and window panes.
• Look for patterns in fabric, wallpaper, flags, or other places that are half one color and half another. How can your child tell that the patterns are half and half?
• Look for designs that are symmetrical.

Vocabulary Terms

Attribute

A characteristic, like color or size

Composing

Putting together

Decomposing

Taking apart

Pattern Blocks

Shapes that include a triangle (green), square (orange), rhombus (blue and tan), trapezoid (red), and hexagon (yellow)

Parallelogram

Four sided polygon with two sets of parallel sides

Polygon

A closed geometric shape having three or more straight sides

Rhombus

Four sided polygon with all sides equal

Square corners

Right angles

Trapezoid

Four sided polygon with one pair of parallel sides

Mathematics Vocabulary Web site

Mathematics Strategy—Seeing Relationships Between Shapes

The goal of many activities in this unit is to help children mentally compose and decompose shapes. Visualizing how a larger unit can be composed of smaller ones and how shapes can be combined to form larger units is the basis of understanding many geometric ideas, from relationships among polygons to area and volume.

When children can put shapes together to form a new shape, and then see that new shape as a new unit with which they can cover or measure, they have created a composite unit. Your child will be doing activities like the one below where they would be asked to predict how many triangles or trapezoids it would take to cover the hexagons.

Source: Investigations in Number, Data, and Space: Shapes, Halves, and Symmetry. Dale Seymour, 1998. (Page 27)

Mathematics Game—Guess My Shape Rule

Materials

A set of Second Grade Shape Cards

Playing the Game

1. The rule maker decides on a Mystery Rule for sorting shapes into two groups: one group fits the rule and the other group doesn’t fit the rule (for example: “has three sides”).



2. The rule maker starts the game by showing several shapes that fit the rule and one shape that does not fit the rule.



3. The players try to find other shapes that fit the rule.



4. With each guess, the shape is placed in one of the two piles (fits rule or doesn’t fit rule). Both piles should be clearly visible. The rule maker says if the placement is correct. If it is not, the shape is placed in the correct group.



5. Players continue to place shapes in the two piles. Once all the shapes have been correctly sorted, players guess the rule.

Get to 2nd Grade Shape Cards (for printing)