Getting Started 
Misconception/Error The student does not have an effective strategy to solve the problem. 
Examples of Student Work at this Level The student attempts to use the standard algorithm but makes significant errors when aligning the digits and says that the answer is 0.33 or 8.25.
The student uses the standard algorithm and aligns the digits correctly but says that the answer is 0.105 due to a regrouping error. 
Questions Eliciting Thinking Can you draw a picture to show me what 0.25 looks like? What about 0.8?
What place is the digit two in? What about the five?
Can you write the numbers in expanded form? What is the value of the digit two? What about the five? 
Instructional Implications Model decimal numbers using manipulatives, concrete models, and drawings. Then model how to add decimal numbers using these models.
Represent decimals on 10 x 10 grids. Then use these representations to show addition of decimals.
Consider using the MFAS Task Decimals In Expanded Form (5.NBT.1.3). 
Moving Forward 
Misconception/Error The student is unable to use a model or drawing or a strategy based on place value, the relationship between addition and subtraction, or properties of operations. 
Examples of Student Work at this Level The student attempts to use a model or drawing or a strategy based on place value, properties of operations, or the relationship between addition and subtraction but cannot successfully complete the addition. 
Questions Eliciting Thinking Can you explain what you have done so far?
How can we use expanded form to help us add?
Can you draw a picture to show me what 0.25 looks like? What about 0.8?
What place is the digit two in? What about the five? 
Instructional Implications Work with the student on becoming proficient at the strategy he or she is using. Then introduce other strategies and provide opportunities for the student to use them. 
Almost There 
Misconception/Error The student is unable to use a strategy based on place value or a model or drawing to explain his or her solution. 
Examples of Student Work at this Level The student correctly adds the numbers using the standard algorithm. When asked why the student aligned the numbers the way he or she did, the student says that you have to align the decimal points. He or she is unable to add the decimal numbers using a strategy based on place value, properties of operations, or relationship between addition and subtraction when prompted.
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Questions Eliciting Thinking Can you draw a picture to model the numbers?
How would you write the numbers in expanded form? Can you use that to help you add? 
Instructional Implications Guide the student to use models or concrete representations to model addition of decimals.
Model how to use the expanded form of a number to add decimals. 
Got It 
Misconception/Error The student provides complete and correct responses to all components of the task. 
Examples of Student Work at this Level The student adds the decimal numbers using a drawing or model or a strategy based on place value, properties of operations, or the relationship between addition and subtraction, getting an answer of 1.05 miles The student is able to explain the strategy used.
The student initially adds using the standard algorithm, but with prompting, the student is able to draw a picture or use place value to add the numbers in another way.
The following are acceptable responses from students who use a strategy, drawing, or model that is based on place value, properties of operations, or relationship between addition and subtraction:
 The student uses the expanded form of the numbers to add and correctly determines that Susan has run 1.05 of a mile so far.
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 The student draws a picture to model 0.25 and 0.8 and correctly uses the model to determine the correct answer. He or she is able to explain the strategy used and how it relates to place value.
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 The student starts with 0.25 and adds 0.10 eight times to get to 1.05. He or she explains that, â€ś0.8 is eight tenths so you can just add a tenth to twentyfive hundredths eight times.â€ť
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Questions Eliciting Thinking How is your model like the standard algorithm?
How is your strategy similar to using a decimal grid? 
Instructional Implications Encourage the student to explore the relationship between the standard algorithm for addition of decimals and the strategy he or she used.
Provide opportunities to add, subtract, multiply, and divide decimals written to the thousandths place.
Consider using the MFAS Task Buying Candy Bars (5.NBT2.7), which assesses a studentâ€™s understanding of multiplying decimals. 