2.NBT.A.1 Flawed Reasoning Place Value

2.NBT A.1 Flawed Reasoning Place Value

Evidence Statement 3.C.4-7 Disti nguish correct explanation/reasoning from that which is flawed, and if there is a flaw in the argument, present corrected reasoning. (For example, some flawed student reasoning is presented and the task is to correct and improve it.)  Content scope: Knowledge and skills articulated in 2.NBT (securely held knowledge from previous grade)

Ribbon Count

The table below shows the number of ribbons a swim team earned during their swim season.

Ribbon Count

Part A

Jasleen says the team won 619 because 3+2+1=6, and 4+6+9=19.

Jasleen is incorrect in her reasoning.

• Explain why Jasleen is incorrect in her thinking.
• Write an equation or equations to find  the correct total number of ribbons earned.

Enter your explanation and equation or equations in the space provided.

Part B

Jasleen says the team won 25 less third place ribbons then first place ribbons because 3-1=2

and 9-4=5.

Jasleen is incorrect in her reasoning.

Explain why Jasleen is incorrect in her thinking.

•  Write an equation or equations to find how many less third place ribbons were earned than first place.

Enter your explanation and equation or equations in the space provided.

Scoring Rubric Part A

Score 2 Student response includes the following 2 elements.

Reasoning component = 1 point

The student explains that Jasleen did not use place value correctly.

Computation component = 1 point

The student provides a correct equation or equations to show how the correct number of ribbons earned. ( 34 + 26 + 19= 79 )

Notes:  If a computation mistake is made, credit cannot be given for the computation component, but 1 point can be given for a valid explanation.

Score 1 Student response include 1 of the above elements.

Score 0 Student response is incorrect or irrelevant.

Scoring Rubric Part B

Score 2 Student response includes the following 2 elements.

Reasoning component = 1 point

The student explains that Jasleen did not use place value correctly.

Computation component = 1 point

The student  provides a correct equation or equations to show how many less third place ribbons were earned. ( 34-19=15 or other valide equation)

Notes:  If a computation mistake is made, credit cannot be given for the computation component, but 1 point can be given for a valid explanation.

Score 1 Student response include 1 of the above elements.

Score 0 Student response is incorrect or irrelevant.