Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), 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.
Measurement Topic
This standard is reported on the report card in these quarters as follows:
1st Grade Students Learning 1st Grade Standards
Quarter 1
Quarter 2
Quarter 3
Quarter 4
Report Card Measurement Topic:Demonstrates understanding of subtraction.
Kindergarten Students Learning 1st Grade Standards
Quarter 1
Quarter 2
Quarter 3
Quarter 4
Report Card Measurement Topic:Demonstrates understanding of subtraction.
About the Math
Skills and concepts below are learning goals for this standard.
Find the difference of two multiples of 10 (e.g. 90 - 40) using models, drawings, hundred charts, and number lines.
Subtract a multiple of 10 from a multiple of 10. (e.g., subtract 90 - 40).
Explain the difference between two multiples of 10 by relating it to subtracting the tens digit.
Explain why the ones place does not change when subtracting multiples of 10.
In order for students to develop strategies for mental computation, they need to see the patterns of subtracting a multiple of 10. In order to do this, they may have to count back by 10 ones and then make the connection that ten ones equal one ten. Seeing the patterns by using a hundreds chart helps students see how to subtract a multiple of ten from another multiple of ten (i.e. 80 - 30). Students may also may connections between counting by 1s and 10s. It is wise to move to subtracting multiples of ten from any two-digit number when students show proficiency with this standard. Moving to the latter will aid the development of mental math and number sense.. Essential vocabulary for this standard includes: add, subtract, 10 more, and 10 less (online dictionaryLinks to an external site., HCPSS Vocabulary CardsDownload HCPSS Vocabulary Cards).
Progression of Standard within Grade 1
This progression informs how to develop the standard within the grade level. This progression is provided by HCPSS Elementary Mathematics.
Progression Throughout Year
Quarter 1
Quarter 2
Quarter 3
Quarter 4
Find the difference of two multiples of 10 (e.g. 90 - 40) using models, drawings, hundred charts, and number lines.
Subtract a multiple of 10 from a multiple of 10. (e.g., subtract 90 - 40).
Explain the difference between two multiples of 10 by relating it to subtracting the tens digit.
Explain why the ones place does not change when subtracting multiples of 10.
Find the difference of two multiples of 10 (e.g. 90 - 40) using models, drawings, hundred charts, and number lines.
Subtract a multiple of 10 from a multiple of 10. (e.g., subtract 90 - 40).
Explain the difference between two multiples of 10 by relating it to subtracting the tens digit.
Explain why the ones place does not change when subtracting multiples of 10.
These tasks can be used with small group or whole group instruction.
Give students base ten blocks and pose the problem 70-20. Ask how could we show this using base ten blocks? Have students work together and solve and record the answer on the board. Continue practicing with various equations recording them on the board each time while they solve so you have several equations for them to look at. Debrief and gather up front to look at all the equations. What do you notice? What is changing? What patterns do you see? How could you use what you noticed to solve 50-20 in your head. Turn and talk to a partner about what you could do solve that in your head. Check it with base ten blocks all together and then have them solve 90-30 in their heads.
Give pairs of students 10 dimes. Tell them I had 90 cents in my pocket. I spent 50 cents on an ice cream. How much do I have left. Ask them to show using the dimes to solve how much is left. Continue practicing and debriefing with the dimes about problems with money (Ashley had 60 cents and spent 20 cents on a gumball. How much does she have left?)
Give students an open number line or a number line ticked by 10s depending on the support needed. Ask how could we show 60-20 on the number line? Where should we start? Which way should we hop? What should we hop by? What is our answer? How do you know? Have them continue to practice in pairs for subtracting 10s equations.
Starting at 90, count backwards by tens, will you land on 33? How do you know?
What number on the hundred chart could you start with and count backwards by ten to land on 33?
Show multiple representations for the subtraction problem 90 - 40 =. (hundred chart, open number line, base ten blocks, etc.) Karly says 90 - 40 is the same as 90 - 10 -10 - 10 -10. Do you agree? Why or why not?
What patterns do you see in these equations: 30 - 10 = 20, 90 - 30 = 60, 50 - 40 = 10
Start with a two-digit multiple of 10 such as 80. Build 80 with base ten blocks (specifically ten rods). Roll a die and subtract that many tens from the 80. How many tens (and what value) do you have left? How many more tens do you need to subtract to get to 0? Enrichment: Use any two-digit number. For example, build 73 and subtract groups of ten.
SLIDE-BASED TASKS
These links are HCPSS created instructional tasks. These tasks are provided in Google slides. These tasks should be used for inspiration and resources, but instruction should start with students having the opportunity to engage with the math first(often involving physical and/or visual models) followed by discussion and explicit instruction to ensure student understanding.
These publications have been provided for each school. They are typically stored in team closets or the media center. Check with your team leader if you cannot find them. Additional copies may be purchased with team or school funds.
Print Resources
Book Thumbnail
Book Title
Grade
Pages
Teaching Student-Centered Mathematics
K-3
Skip-Count Patterns, Activity 5.10, Page 138 More and Less on the Hundreds Chart, Activity 5.11, Page 139 Models with the Hundreds Chart, Activity 5.12, Page 139 Expanded Lesson Exploring Subtraction Strategies, Page 184-185
These resource sheets can be used for independent practice, homework, or assessment. They are intended to reinforce procedures and concepts. They should not be used as a source of direct instruction or whole-group practice.
Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), 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.
Measurement Topic
The standard is reported on the report card through these measurement topics. Expand the measurement topic for a description of what students who meet expectation are able to do.
1st Grade Students Learning 1st Grade Standards by Measurement Topic