Decimals - Adding and Subtracting

Learning Topics: 

Introduction, reading and writing, comparing, ordering, estimating sums, adding, estimating differences, subtracting, solve real-world problems.

Learning Objectives for all Adding and Subtracting Decimals lessons in Unit 12.


Introduction to Decimals

The student will be able to:

  • Define decimal, mixed number, whole number, fraction, place value, expanded form, decimal digits and equivalent decimals.
  • Identify the whole number and fractional parts of a decimal.
  • Identify the purpose of using decimals.
  • Recognize connections between decimal numbers and place value.
  • Write decimals in expanded form.
  • Write whole numbers as decimals.
  • Recognize that writing a decimal with a zero in the one's place helps us remember that the number is less than one.
  • Recognize that the decimal point is used to separate the whole number part from the fractional part.
  • Apply decimal concepts to complete five interactive exercises.

Reading and Writing Decimals

The student will be able to:

  • Define equivalent fractions.
  • Write mixed numbers as decimal numbers.
  • Write phrases as decimal numbers.
  • Recognize that decimal places change by a factor of ten.
  • Recite and write decimal numbers using words.
  • Distinguish between the value of two hundred thousand, two hundred thousandths and two hundred-thousandths.
  • Distinguish between the written phrases decimals such as for 0.110 and 0.0100.
  • Apply reading and writing of decimals to complete five interactive exercises.

Comparing Decimals

The student will be able to:

  • Identify the equality and the inequality symbols used to compare two decimals.
  • Compare two decimals using a place-value chart.
  • Express the comparison using the proper symbols.
  • Recognize the importance of writing one decimal below the other when comparing two decimals.
  • Recognize that writing one or more zeros to the right of the last digit of a decimal does not change its value.
  • Compare two decimals without a place-value-chart.
  • Describe the procedure for comparing two decimals.
  • Apply the procedure for comparing two decimals to complete five interactive exercises.

Ordering Decimals

The student will be able to:

  • List three or more decimals in order from least to greatest using a place-value chart.
  • Recognize the need to compare decimals two at a time when ordering three or more decimals.
  • List three or more decimals with varying places in order from least to greatest.
  • Recognize the need to write one decimal beneath the other when ordering decimals.
  • Recognize the need to place a number in a circle to the right of each decimal when ordering decimals.
  • Solve non-routine and open-ended problems by comparing and ordering of decimals.
  • Describe the procedure for ordering three or more decimals from least to greatest
  • Apply the procedure for ordering three or more decimals to complete five interactive exercises.

Estimating Decimal Sums

The student will be able to:

  • Define estimate, overestimate and underestimate.
  • Describe the front-end and rounding strategies for estimating decimal sums.
  • Apply these strategies to estimate decimal sums.
  • Recognize that the use of different strategies can result in different estimates.
  • Determine if an estimate is an overestimate or an underestimate by comparing it with the actual sum.
  • Explain the difference between an overestimate and an underestimate.
  • Apply estimation strategies to complete five interactive exercises.

Adding Decimals

The student will be able to:

  • Examine examples of adding two decimals with varying places after the decimal point.
  • Examine examples of adding three decimals with varying places after the decimal point.
  • Examine examples of adding currency.
  • Describe how to carry when adding decimals.
  • Examine examples of adding decimals in which carrying is performed more than once.
  • Describe the procedure for adding two or more decimals.
  • Perform addition of two or more decimals to find the sum.
  • Recognize the importance of lining up all the decimal points in a column before adding.
  • Connect decimals and money.
  • Apply decimal addition strategies to complete five interactive exercises.

Estimating Decimals Differences

The student will be able to:

  • Recognize that estimation is an important tool in our daily lives.
  • Estimate decimal differences by rounding to various places.
  • Determine whether an estimate is reasonable or unreasonable.
  • Develop a sense of which place to round to when estimating decimal differences.
  • Recognize that estimates may vary for the same problem.
  • Recognize, when estimating differences, the estimate should not exceed the original numbers.
  • Apply estimation strategies to complete five interactive exercises.

Subtracting Decimals

The student will be able to:

  • Examine simple examples of subtracting two decimals in which borrowing is performed.
  • Examine examples of subtracting two decimals with varying places, and in which borrowing is performed.
  • Recognize the importance of writing one or more extra zeros to the right so that both decimals have the same number of decimal digits.
  • Describe the procedure for subtracting decimals.
  • Examine examples of subtracting currency.
  • Perform subtraction of decimals
  • Connect decimals and money.
  • Apply decimal subtraction strategies to complete five interactive exercises.

Solving Decimal Word Problems

The student will be able to:

  • Examine examples of real-world problems involving decimals.
  • Examine the solution presented for each problem.
  • Examine five interactive exercises with real-world problems involving decimals.
  • Analyze each problem to identify the given information.
  • Formulate a strategy for solving each problem.
  • Apply decimal strategies to solve problems.

Practice Exercises

The student will be able to:

  • Examine ten interactive exercises for all topics in this unit.
  • Determine which strategies and procedures are needed to complete each practice exercise.
  • Compute answers by applying appropriate decimal strategies and procedures.
  • Self-assess knowledge and skills acquired from this unit.

Challenge Exercises

The student will be able to:

  • Evaluate ten interactive exercises with word problems for all topics in this unit.
  • Determine which strategies and procedures are needed to complete each exercise.
  • Apply decimal strategies and procedures to solve routine and non-routine word problems.
  • Synthesize all information presented in this unit.
  • Connect decimals to the real world.
  • Develop problem-solving skills.

Solutions

The student will be able to:

  • Examine the solution for each exercise presented in this unit.
  • Identify which solutions need to be reviewed.
  • Compare solutions to completed exercises.
  • Identify and evaluate incorrect answers.
  • Amend and label original answers.
  • Identify areas of strength and weakness.
  • Decide which strategies and procedures need to be reviewed from this unit.

IXL