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# Why 10? - PowerPoint PPT Presentation

Why 10?. Why 10? O ur number system is based and built by 10’s. It originated because we have 10 fingers—how the first person began counting. Presented by Joan Kernan and Donna Kouri. Research for Number Sense. National Council for Mathematics Elementary and Middle School Mathematics:

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Presentation Transcript

### Why 10?

Why 10? Our number system is based and built by 10’s. It originated because we have 10 fingers—how the first person began counting.

Presented by Joan Kernan and Donna Kouri

National Council for Mathematics

Elementary and Middle School Mathematics:

Teaching Developmentally

Student should:

• Understand numbers, ways of representing numbers, relationships among numbers, and number systems

• Understand meanings of operations and how they relate to one another

• Compute fluently and make reasonable estimates

Key ideas include:

• Recognize “how many” in a set (Cardinality)

• Decomposing - Examples 7 is composed of 4 and 3 as well as 5 and 2, is less than 9 and more than 5, is 3 away from 10, can be recognized quickly, will extend to the understanding of 17, 57, and 370

• Encounter a variety of meanings for addition and subtraction

• Fluency requires a balance and connection between conceptual understanding and computational proficiency

We will be looking closely at numbers, and

how much each number is worth; what makes

that number that number.

This session is designed to help young elementary children see numbers within numbers. The goal is NOT to master these techniques within one math lesson.

The games today will strengthen the child’s understanding of the values of numbers.

This is playing with numbers and learning during the journey.

The idea of Seeing Numbers is the ability to recognize the value of a number without counting.

This is officially known as Subitizing. By seeing numbers as groups rather than the result of counting single units or counting on, children are able to conceptualize groups of numbers and how they can be combined to make new numbers.

The value of this demonstration:

Large-- need a volunteer

distinguish between the immediate known and

and the cards with hesitation

Small– individualizing the instruction

• Whole Group Demo

• Focus on questioning strategies for

students

Shows numbers with one color.

Allows you to look at visual patterns/placement of two-sided counters

Show numbers with two different colors

• This extends the activity and is using more techniques: visually adding, plus one, etc

The Rekenrek was designed

at the Freudenthal Institute

in Holland.

The term Rekenrek means calculating frame or arithmetic rack.

The Rekenrek may resemble

an abacus. The abacus is based

on place value columns.

The Rekenrek features two rows of ten 10 beads and each row is broken into two sets of five.

• A large Rekenrek can be used in both whole and small group instruction.

• For varying grade levels, there is a plethora of resources on the web. We found many demonstrations on YouTube.

Rekenreks

You will need:

• Two rectangular boards

• Two chenille stems

• 10 beads of one color

• 10 beads of another color

• 2 stickers to mark the “read the numbers” area

• Any Ahh Ha! Moments?

• Door Prizes

… and the winners are…