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Welcome to Subtraction! – Understanding subtraction – Subtraction means taking away from a group – Using number lines for subtraction – A number line helps us see the ‘taking away’ – Subtracting within 20 – We’ll subtract numbers from 1 to 20 – Practice with subtraction sentences – We’ll write sentences to show subtraction | This slide introduces the concept of subtraction to second graders, emphasizing its role in determining the remaining quantity after taking some away. The use of number lines is a visual strategy to help students understand and perform subtraction, especially within the range of 20. Encourage students to visualize the subtraction process as a backward movement along the number line. Provide examples of subtraction sentences, such as ‘If we have 15 apples and we eat 5, how many do we have left?’ (15 – 5 = 10). Practice with the class by creating subtraction sentences together and solving them using number lines drawn on the board or on paper. This will help solidify their understanding of subtraction as a concept and a practical skill.

Understanding Subtraction – Subtraction means taking away – It finds the difference between numbers – If you have 5 apples and eat 2, you have 3 left. – ‘Difference’ is the answer in subtraction – For example, 10 – 6 = 4, so the difference is 4. – Using number lines to subtract – We can ‘jump back’ on the line from 20 to find the difference. | This slide introduces the concept of subtraction to second graders. Subtraction is explained as the process of taking one number away from another, which helps us understand how much less one amount is compared to another. Emphasize that the result of a subtraction is known as the ‘difference’. Use simple, relatable examples like having a certain number of items and then losing some to illustrate the point. Introduce the number line as a visual and interactive tool to help students grasp the concept of subtraction by ‘jumping back’ from a starting point. This sets the foundation for further activities where students will practice using number lines to perform subtraction.

Subtracting with Number Lines – What is a number line? – A straight line with numbers at equal spaces – Counting forward and backward – For addition, we count forward; for subtraction, we count backward – Using number lines to subtract – To subtract, we start at a number and hop backward – Practice subtraction up to 20 | This slide introduces the concept of a number line and its application in subtraction for second graders. Begin by explaining what a number line is and how it is organized. Emphasize that the spaces between numbers are equal, which helps in accurate counting. Demonstrate counting forwards for addition and then counting backwards for subtraction. Use examples like 15 – 4, where you start at 15 on the number line and make 4 hops backwards to land on 11. Encourage students to practice with different subtraction problems up to 20, ensuring they understand the concept of ‘taking away’ by moving to the left on the number line. Provide hands-on activities with physical number lines for students to interact with.

Subtraction Sentences with Number Lines – What is a subtraction sentence? – It’s a math story showing taking away. – Example: 5 – 3 = 2 – Starting with 5, count back 3 steps to land on 2. – Writing our subtraction stories – We’ll create our own examples as a class. – Using number lines to subtract – Draw a line with numbers and hop backwards to subtract. | This slide introduces the concept of subtraction sentences to second graders, explaining them as stories where something is taken away. Use the example 5 – 3 = 2 to illustrate how subtraction works by counting backwards. Engage the class by writing subtraction sentences together, using objects or fingers to represent the numbers. Introduce a number line as a visual aid to help students understand the concept of ‘taking away’ by physically moving backwards on the line. Encourage students to draw their own number lines and practice subtracting by hopping back the required number of steps. This hands-on activity will help solidify their understanding of subtraction.

Subtracting with Number Lines – Start at the first number – Place a marker on the first number of our subtraction problem. – Count backwards on the line – Each hop represents subtracting one. Hop as many times as the second number. – Number of jumps equals subtraction – If our sentence is 15 – 4, we make 4 jumps backwards. – Landing point is the answer – Check the number we land on; that’s how many are left. | This slide is aimed at helping second-grade students understand how to use a number line to solve subtraction problems up to 20. Begin by explaining that a number line is a visual tool that can help us ‘see’ the subtraction process. Demonstrate with an example, such as 12 – 3, by starting at 12 on the number line and making 3 jumps backwards to land on 9, which is the answer. Encourage students to practice with different subtraction sentences and to use their fingers to ‘jump’ along the number line as they count backwards. This kinesthetic approach helps solidify the concept of ‘taking away’ in subtraction.

Let’s Practice Subtraction with Number Lines! – Example: Subtract 7 – 4 – Start at 7 on the number line – We begin our subtraction journey from number 7 – Jump back 4 spaces – Each jump back is one less, so we make 4 jumps back – Find the answer: 7 – 4 = 3 – After 4 jumps back, we land on number 3, which is our answer | This slide is an interactive class activity to help students understand subtraction using number lines. Begin by explaining the concept of a number line and how it can be used for subtraction. Show the example of subtracting 4 from 7. Guide the students to visualize starting at 7 on the number line and making 4 jumps backwards to find the answer. Each jump represents subtracting one. After the jumps, we land on 3, which is the solution to 7 – 4. Encourage students to use their fingers to count the jumps on their own number lines. Prepare to assist students who may struggle with the concept of ‘jumping back’ and ensure they understand that each jump represents subtracting one unit. Have additional examples ready for students to try, such as 10 – 6, 8 – 5, and 15 – 4, to reinforce the concept.

Your Turn to Try: Subtraction with Number Lines – Use the number line for subtraction – Start at the first number – If we have 15 – 4, start at 15 on the number line – Count backwards to subtract – Move 4 steps back to find the answer – Share your answers with the class | This slide is an interactive class activity where students will apply their knowledge of subtraction using number lines. Provide each student with a number line that goes up to 20. Encourage them to pick a subtraction sentence, such as 12 – 7, and place their finger on the larger number (12). They should then count backwards 7 steps to find the answer. After completing the exercise, ask students to share their subtraction sentence and how they used the number line to find the answer. This will help reinforce their understanding and allow for peer learning. Possible variations of the activity could include using physical number lines on the floor, where students can walk the steps, or creating a number line with a string and beads.

Class Activity: Number Line Hopscotch – Let’s play Number Line Hopscotch! – Hop on the number line to subtract – Start at a number, hop backwards to subtract – Understand subtraction actively – Visual and physical way to learn subtraction – Each student gets a turn | This activity is designed to combine physical activity with learning to enhance students’ understanding of subtraction. Set up a number line on the floor with tape or chalk. Students will start at a number and physically hop backwards the number of spaces they are subtracting. For example, if the problem is 10 – 4, they start at 10 and hop back 4 spaces to land on 6. This visual and kinesthetic approach helps solidify the concept of ‘taking away’ in subtraction. Prepare different subtraction problems for each student, ensuring they are all within the 0-20 range. Encourage students to count out loud as they hop to reinforce the concept. Observe the students as they hop to assess their understanding and provide guidance where necessary.

Subtraction Review with Number Lines – Great work on number line subtraction! – Subtraction shows how many are left – If you have 10 apples and eat 2, how many do you have left? – Keep practicing subtraction at home – Try subtracting numbers from 1 to 20 – You’re becoming a subtraction star! | This slide is a conclusion and a recap of the lesson on using number lines for subtraction. It’s meant to reinforce the concept that subtraction is a way to find out how many items remain after some are taken away. Encourage the students to continue practicing at home with different numbers up to 20 to solidify their understanding. Remind them that the more they practice, the better they will get at it. You can suggest that parents help their children by creating simple subtraction problems for them to solve using number lines drawn on paper or found in workbooks.