The purpose of this Number Talk is for students to divide a whole number by a tenth and a hundredth, presented both as fractions and as decimals. This prepares students to work with and understand quotients of whole numbers by decimals in this and future lessons.
Launch
Display one problem.
“Give me a signal when you have an answer and can explain how you got it.”
1 minute: quiet think time
Teacher Instructions
Record answers and strategy.
Keep problems and work displayed.
Repeat with each problem.
Student Task
Find the value of each expression mentally.
1÷101
2÷101
1÷0.01
2÷0.01
Sample Response
10: There are 10 tenths in 1 whole.
20: There are twice as many tenths in 2 wholes.
100: There are 100 hundredths in 1 whole.
200: There are twice as many hundredths in 2 wholes.
Activity Synthesis (Teacher Notes)
“What is the same about these expressions? What is different?” (They all show a whole number divided by a number less than 1. Some have decimals and some have fractions, but the decimals and fraction are all 1 of some unit. They all have a value that is a whole number.)
Standards
Addressing
5.NBT.7·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.
5.NBT.B.7·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.
5.NF.7.b·Interpret division of a whole number by a unit fraction, and compute such quotients. <em>For example, create a story context for 4 ÷ (1/5), and use a visual fraction model to show the quotient. Use the relationship between multiplication and division to explain that 4 ÷ (1/5) = 20 because 20 × (1/5) = 4.</em>
5.NF.B.7.b·Interpret division of a whole number by a unit fraction, and compute such quotients. <span>For example, create a story context for <span class="math">\(4 \div (1/5)\)</span>, and use a visual fraction model to show the quotient. Use the relationship between multiplication and division to explain that <span class="math">\(4 \div (1/5) = 20~\)</span> because <span class="math">\(20 \times (1/5) = 4\)</span>.</span>
15 min
20 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
Divide Whole Numbers by 0.1 and 0.01
10 min
Narrative
The purpose of this Number Talk is for students to divide a whole number by a tenth and a hundredth, presented both as fractions and as decimals. This prepares students to work with and understand quotients of whole numbers by decimals in this and future lessons.
Launch
Display one problem.
“Give me a signal when you have an answer and can explain how you got it.”
1 minute: quiet think time
Teacher Instructions
Record answers and strategy.
Keep problems and work displayed.
Repeat with each problem.
Student Task
Find the value of each expression mentally.
1÷101
2÷101
1÷0.01
2÷0.01
Sample Response
10: There are 10 tenths in 1 whole.
20: There are twice as many tenths in 2 wholes.
100: There are 100 hundredths in 1 whole.
200: There are twice as many hundredths in 2 wholes.
Activity Synthesis (Teacher Notes)
“What is the same about these expressions? What is different?” (They all show a whole number divided by a number less than 1. Some have decimals and some have fractions, but the decimals and fraction are all 1 of some unit. They all have a value that is a whole number.)
Standards
Addressing
5.NBT.7·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.
5.NBT.B.7·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.
5.NF.7.b·Interpret division of a whole number by a unit fraction, and compute such quotients. <em>For example, create a story context for 4 ÷ (1/5), and use a visual fraction model to show the quotient. Use the relationship between multiplication and division to explain that 4 ÷ (1/5) = 20 because 20 × (1/5) = 4.</em>
5.NF.B.7.b·Interpret division of a whole number by a unit fraction, and compute such quotients. <span>For example, create a story context for <span class="math">\(4 \div (1/5)\)</span>, and use a visual fraction model to show the quotient. Use the relationship between multiplication and division to explain that <span class="math">\(4 \div (1/5) = 20~\)</span> because <span class="math">\(20 \times (1/5) = 4\)</span>.</span>