Exploring 2-Digit Addition with Open Number Lines

Mrs. T from PS11 demonstrates how to solve a two-digit addition problem using an open number line. She explains the concept of an open number line and provides a step-by-step guide to solving 45 + 32 by adding tens and ones separately. An alternative method using a large jump to add tens is also shown. The tutorial emphasizes visual representation and place value strategies.

What is an open number line?

• A number line that can only be used digitally.

• A number line with no numbers or markers, added as we work.

• A number line with predefined numbers and markers.

• A graphical tool only for subtraction.

What is the starting number in the example provided?

• 32

• 45

• 10

• 77

How many tens are added first in the example?

• Two tens

• Three tens

• Four tens

• Five tens

What does each jump represent when adding tens?

• 10

• 15

• 20

• 5

How many ones are added after the tens?

• One

• Four

• Two

• Three

What is the final sum of 45 plus 32?

• 75

• 80

• 77

• 82

What alternative method is shown for adding tens?

• Using multiplication

• Adding each ten separately

• Subtracting then adding back

• Adding all tens in one jump

What is the sum after adding 30 all at once to 45?

• 65

• 85

• 75

• 95

Why might students choose to add all tens at once?

• It's a slower process.

• It's only for advanced students.

• It requires less space on the number line.

• It's more challenging.