Mathematics experiences in early childhood settings should concentrate on (1) number (which includes whole number, operations, and relations) and (2) geometry, spatial relations, and measurement, with more mathematics learning time devoted to number than to other topics. Mathematical process goals should be integrated in these content areas.

—Mathematics Learning in Early Childhood, National Research Council, 2009

3. Decompose numbers less than or equal to 10 into pairs in more than one way, e.g., by using objects or drawings, and record each decomposition by a drawing or equation.

(Kindergarten students should see addition and subtraction equations, and student writing of equations in kindergarten is encouraged, but is not required.)

What is a big idea?

NCTM (2000, p. 19): “... worthwhile tasks should be intriguing, with a level of challenge that invites speculation and hard work.”

Such tasks should enable their use at different grade levels and be associated with any of the 25 elements of the content-process standards matrix.

Four red/yellow counters can be arranged in 16 ways.

Four can be partitioned in positive integers in

8 = 24 - 1 ways.

Generalization:

Positive integer N can be partitioned in positive integers in 2N – 1 ways.

What are the chances that

A combination of four counters does not include a red one?

No two red counters appear in a row?

A combination of four counters begins with a red one?

A combination of four counters ends with a red one?

2. Compose two-dimensional shapes (rectangles, squares, trapezoids, triangles, half-circles, and quarter-circles) or three-dimensional shapes (cubes, right rectangular prisms, right circular cones, and right circular cylinders) to create a composite shape, and compose new shapes from the composite shape.

8. Solve real world and mathematical problems involving perimeters of polygons, including finding the perimeter given the side lengths, finding an unknown side length, and exhibiting rectangles with the same perimeter and different areas or with the same area and different perimeters.

3. Recognize a line of symmetry for a two-dimensional figure as a line across the figure such that the figure can be folded along the line into matching parts. Identify line-symmetric figures and draw lines of symmetry.

Using 10 linking cubes, construct 5 towers and arrange them from the lowest to the highest. There may be more than one way to do that. Construct all such combinations of 5 towers using the 10 cubes. Record your combinations (the sets of towers). Describe what you have found.

Area = 10, Perimeter = 16

Area = 10 Perimeter = 16

10=1+1+2+3+3 16=5+3+2+1+1+1+2+1

10=1+2+2+2+3 16=5+3+1+1+3+1+1+1

1 1 2 3 3

2

3

5

1 2 2 2 3

1

4

5

Area = 10, Perimeter = 22

Area = 10, Perimeter = 20

10=1+1+1+2+5 20=5+5+1+3+1+1+3+1

10=1+1+1+1+6 22=5+6+1+5+4+

1

1

1

1

2

5

1

1

1

1

1

5

1 1 1 2 5

1 1 1 1 6

Area = 10, Perimeter = 18

10=1+1+1+3+4 18=5+4+1+1+1+2+3+1

Area = 10, Perimeter = 18

10=1+1+2+2+4 18=5+4+1+2+2+1+2+1

1 1 1 3 4

1 1 2 2 4

1

2

2

5

1

1

3

5

10=2+2+2+2+2 14=5+2+5+2

Area = 10, Perimeter = 14

2 2 2 2 2

5

5

COMMON CORE STATE STANDARDS

Elementary students can construct arguments using concrete referents such as objects, drawings, diagrams, and actions. Such arguments can make sense and be correct, even though they are not generalized or made formal until later grades.

Partition in three parts turns into partition with the largest part three

Mathematically proficient students can ... draw diagrams of important features and relationships ... Younger students might rely on using concrete objects or pictures to help conceptualize and solve a problem. Mathematically proficient students check their answers to problems using a different method, and they continually ask themselves, “Does this make sense?”

Why is perimeter always an even number?

Why can Ferrers-Young diagrams with the same perimeter and area be created?

May it be the case for partition into two parts?

10=1+2+4+2+1P=18=5+1+1+1+1+2+1+2+1+1+1+1

A=10=2+1+4+1+2 P=22=5+2+1+1+1+3+1+3+1+1+1+2

area and perimeter are the same (numerically)

mean, median, and mode height are the same

the set is symmetrical

the set can be rearranged to be symmetrical

perimeter is an odd number

perimeter is an even number

Manipulative materials for challenging tasks

Extending CCSS

Using worthwhile tasks

Connecting mathematics across grades

Preparing students for upper grades

Making mathematics learning fun