Add, subtract, multiply, and divide decimals to hundredths, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.


Learning Targets

  • I can add, subtract, multiply, and divide decimals.
  • I can explain how I computed with decimals using concrete models or drawings.
intermediate_rubric.png
Formative Assessment Rubric

Assessment Tasks

(These tasks can be used for formative or summative data. Visit Assessing Students for more information.)

Exit ticket: Insert a decimal point in the product to make the number sentence true. Explain your reasoning.
2.43 X 5.1 = 12393
3.5 X 7.64 = 2674

Paul added these decimals: .4 + .7 and wrote .11 as the answer. Explain to Paul why he is incorrect.

I added 3 decimal numbers together to make 6. What might the three numbers be? Explain your answer.




Tasks Adapted from Smarter Balance and/or PARCC Assessment Sample Tasks


Intervention:


component_skills_text.png

4.NF.6

Use decimal notation for fractions with denominators 10 or 100. For example, rewrite 0.62 as 62/100; describe a length as 0.62 meters; locate 0.62 on a number line diagram.

4.NBT.6

Fluently add and subtract multi-digit whole numbers using the standard algorithm.

5.NBT.5

Fluently multiply multi-digit whole numbers using the standard algorithm.

5.NBT.6

Find whole-number quotients of whole numbers with up to four-digit dividends and two-digit divisors, using strategies based on place value, the properties of operations, and/or the relationship between multiplication and division. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.


Other Common Misconceptions

Students often have difficulty determining what to do with the decimal point when multiplying decimals. Often they have been told to count the number of decimal places in the two factors and move the decimal that number of places to the left of the product. Students may encounter problems where this does not hold true.
For example, if we ask a child where to place the decimal point in 3.5 X 7.64 = 2674, if they only count the places, they will write 2.674. But if they understand the value of the decimals, they know that 3 x 7 = 21, so the answer has to be larger than 2.674.

Enrichment:




Essential Skills and Knowledge (from MSDE Common Core Frameworks)


Questions/Comments:

Contact John SanGiovanni at jsangiovanni@hcpss.org.

Creative_Commons.pngUse and Sharing of HCPSS Website and Resources
Howard County Public Schools Office of Elementary Mathematics Curricular Projects has licensed this product under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.