Subtraction Within 20 Video Lessons for 1st Grade

Video-based learning: visual explanations, step-by-step tutorials, and interactive demonstrations for mastering subtraction within 20.

Video Lesson Activities 1 to 3
1 Counting Back Video
Lesson 1
Watch a video demonstrating the counting back strategy for subtraction.
Example: 15 - 7, start at 15 and count back 7 numbers.
Definition:

Counting Back Strategy: A subtraction method where you start with the minuend and count backward by the subtrahend.

Counting Back Method:
  1. Start with the minuend (larger number)
  2. Count backward by the subtrahend (smaller number)
  3. Land on the difference
  4. Verify by adding the difference to the subtrahend

Counting Back Strategy

Visual demonstration of 15 - 7 = 8

Video Examples:

1
Start at 15
2
Count back: 14, 13, 12, 11, 10, 9, 8
3
Result: 8
Step 1: Identify the starting number

Minuend is 15

Step 2: Count back by the subtrahend

Count back 7 numbers from 15

Step 3: Identify the landing number

After counting back 7, you land on 8

Final answer:

15 - 7 = 8

Applied rules:

• Sequential Counting: Each step reduces the number by 1

• Accurate Counting: Count each step individually

• Verification: Add the answer to the subtrahend to check

2 Number Line Video
Lesson 2
Watch a video showing subtraction using a number line.
Example: 18 - 9, start at 18 and move 9 spaces to the left.
Definition:

Number Line Strategy: A visual method using a number line to represent subtraction as movement to the left.

Number Line Strategy

Visual demonstration of 18 - 9 = 9

Video Examples:

1
Locate 18 on the number line
2
Move 9 spaces to the left
3
Land on 9
Step 1: Locate the minuend

Find 18 on the number line

Step 2: Move left by the subtrahend

Move 9 spaces to the left from 18

Step 3: Identify the landing point

Where you land is the answer

Final answer:

18 - 9 = 9

Applied rules:

• Directional Movement: Subtraction moves left on the number line

• Consistent Spacing: Each step represents one unit

• Visual Confirmation: See the distance between numbers

3 Fact Family Video
Lesson 3
Watch a video explaining fact families and how they help with subtraction.
Example: For 16 - 8, think about 8 + 8 = 16.
Definition:

Fact Family: A group of related addition and subtraction facts using the same three numbers.

Fact Family Strategy

Visual demonstration of 16 - 8 = 8 using 8 + 8 = 16

Video Examples:

1
Identify the fact family (8, 8, 16)
2
Use addition fact: 8 + 8 = 16
3
Derive subtraction: 16 - 8 = 8
Step 1: Identify the three numbers

For 16 - 8, the numbers are 8, 8, and 16

Step 2: Use related addition fact

Since 8 + 8 = 16, then 16 - 8 = 8

Step 3: Verify the relationship

Check that 8 + 8 = 16 and 16 - 8 = 8

Step 4: Complete the fact family

Know all 4 related facts

Final answer:

16 - 8 = 8

Applied rules:

• Inverse Operations: Addition and subtraction are opposites

• Part-Part-Whole: Three numbers relate as parts and whole

• Verification: Use addition to check subtraction answers

Video-Based Learning Methods and Strategies
Minuend - Subtrahend = Difference
Subtraction Structure
Method 1
Counting Back
Start with larger number
Method 2
Number Line
Visual representation
Method 3
Fact Families
Use related facts
Key definitions:

Video-Based Learning: Using educational videos to present mathematical concepts through visual and auditory means

Subtraction: The operation of taking away one number from another to find the difference

Minuend: The number being subtracted from

Subtrahend: The number being subtracted

Difference: The result of subtraction

Fact Family: Related addition and subtraction facts using the same numbers

Video-Based Learning Strategies:
  1. Active Viewing: Watch videos with focused attention and engagement
  2. Note Taking: Write down key steps and strategies shown in videos
  3. Pause and Practice: Stop videos to practice demonstrated strategies
  4. Repetition: Watch videos multiple times for better understanding
  5. Verification: Check video examples with own calculations
  6. Application: Use learned strategies on new problems
Tip 1: Watch videos in a quiet environment free from distractions.
Tip 2: Pause videos to practice the strategy before continuing.
Tip 3: Take notes on the steps demonstrated in videos.
Tip 4: Rewatch videos to reinforce learning and build fluency.
Benefits: Visual demonstrations, repeated viewing, self-paced learning, multi-sensory engagement, accessibility for different learning styles.
Key Concepts: Subtraction as taking away, part-whole relationships, inverse relationship with addition.
Important Subtraction Facts:

• Any number minus itself equals zero: n - n = 0

• Any number minus zero equals itself: n - 0 = n

• Subtraction is the inverse of addition: a - b = c means c + b = a

• Fact families: 3 numbers create 4 related facts (e.g., 5, 3, 8 → 5+3=8, 3+5=8, 8-5=3, 8-3=5)

Detailed Summary and Key Concepts
4 Comprehensive Summary
Video-Based Learning Definitions:

Subtraction: The operation of taking away one number from another to find the difference.

Minuend: The number from which another number is subtracted (the first number in a subtraction problem).

Subtrahend: The number that is subtracted (the second number in a subtraction problem).

Difference: The result of a subtraction problem.

Video-Based Learning: Using educational videos to present mathematical concepts through visual and auditory means.

Counting Back: A subtraction strategy where you start with the minuend and count backward by the subtrahend.

Number Line: A visual tool showing numbers in order to represent mathematical operations.

Fact Family: A group of related addition and subtraction facts using the same numbers.

Core Subtraction Rules:

• Identity Property: n - 0 = n (subtracting zero doesn't change the number)

• Zero Property: n - n = 0 (any number minus itself equals zero)

• Inverse Relationship: If a - b = c, then c + b = a

• Order Matters: Subtraction is not commutative (a - b ≠ b - a)

• Subtraction Facts: Know basic facts from 0-20 fluently

Video-Based Subtraction Methods:
  1. Counting Back: Start with the minuend and count backward by the subtrahend
  2. Number Line: Move left on a number line from the minuend
  3. Fact Families: Use related addition facts to solve subtraction
  4. Think Addition: For 13 - 8, think "8 plus what equals 13?"
  5. Decompose Numbers: Break apart numbers to make subtraction easier
  6. Doubles Strategy: Use doubles facts to solve near-doubles (14 - 7 = 7)
Step-by-Step Video Learning Process:
  1. Prepare for the video lesson (quiet space, materials ready)
  2. Watch the video with focused attention
  3. Take notes on key strategies and steps
  4. Pause to practice demonstrated problems
  5. Verify examples shown in the video
  6. Apply learned strategies to new problems
  7. Re-watch for reinforcement and clarification
Basic Video Examples:

5 - 2 = 3 (counting back: 5, 4, 3)

10 - 4 = 6 (think addition: 4 + ? = 10)

8 - 8 = 0 (zero property)

7 - 0 = 7 (identity property)

Intermediate Video Examples:

15 - 7 = 8 (fact family: 7 + 8 = 15)

18 - 9 = 9 (doubles relationship)

16 - 8 = 8 (halving relationship)

14 - 6 = 8 (think addition: 6 + 8 = 14)

Advanced Video Examples:

17 - 8 = 9 (think: 8 + 9 = 17)

14 - 6 = 8 (decompose: 14 - 4 - 2 = 8)

19 - 12 = 7 (counting back or addition thinking)

13 - 5 = 8 (pattern recognition: 10 - 5 = 5, so 13 - 5 = 8)

Common Mistakes: Getting distracted during videos, not pausing to practice, rushing through without understanding, forgetting to take notes.
Memory Tricks: Use doubles facts, think addition, practice fact families regularly, look for patterns.
Key Takeaways:
  • Video demonstrations provide clear visual examples
  • Multiple viewing reinforces learning
  • Self-paced learning accommodates individual needs
  • Multi-sensory approach enhances understanding
  • Pause and practice improves retention
5 Video Learning Strategies
Video Learning Elements:

Active Engagement: Interacting with video content rather than passively watching

Self-Pacing: Controlling the speed and timing of learning

Repetition: Re-watching content to reinforce understanding

Application: Using learned strategies on new problems

Effective Video Learning Strategies:
  1. Pre-Watching Preparation: Gather materials and prepare learning space
  2. Active Watching: Focus attention and engage with content
  3. Note Taking: Write down key points and strategies
  4. Pause and Practice: Stop to try the demonstrated strategy
  5. Post-Watching Review: Summarize what was learned
  6. Application Practice: Use strategies on new problems
Learning Guidelines:

• Watch in distraction-free environment

• Take notes during the video

• Practice strategies immediately

• Re-watch for reinforcement

• Apply to new problems

Video Learning Success Indicators:

• Ability to replicate demonstrated strategies

• Improved problem-solving accuracy

• Increased confidence in math abilities

• Successful application to new problems

Advanced Video Applications and Mastery
A - B = C
Basic Subtraction
Extended definitions:

Subtraction Fluency: The ability to recall subtraction facts within 20 instantly and accurately.

Visual-Spatial Learning: Using visual elements to understand mathematical concepts.

Multi-Sensory Integration: Combining visual, auditory, and kinesthetic learning modalities.

Transfer Skills: Applying video-learned knowledge to solve more complex problems.

Self-Regulated Learning: Managing one's own learning process through video content.

Metacognitive Awareness: Understanding one's own thinking and learning processes.

Advanced Video Learning Strategies:
  1. Comparative Analysis: Compare different strategies shown in videos
  2. Pattern Recognition: Identify and utilize numerical relationships shown visually
  3. Self-Explanation: Explain video content in your own words
  4. Strategy Selection: Choose the most efficient method for each problem
  5. Verification Techniques: Check answers using multiple methods
  6. Reflection: Evaluate which strategies work best for you
Tip 1: Create personalized sets of challenging problems for targeted video practice.
Tip 2: Use multiple videos to see different approaches to the same concept.
Tip 3: Practice subtraction in context through video word problems.
Tip 4: Use video pause time to predict the next step in problem solving.
Common misconceptions: Thinking videos are just entertainment, believing math videos don't require active engagement, ignoring the importance of practice after watching.
Long-term benefits: Foundation for advanced math, improved visual-spatial skills, enhanced self-directed learning, better mathematical reasoning.
Subtraction Properties and Relationships:

• Commutative Property does NOT apply: a - b ≠ b - a

• Associative Property does NOT apply: (a - b) - c ≠ a - (b - c)

• Compensation Principle: If you add the same amount to both numbers, the difference stays the same

• Connection to Addition: Every subtraction problem can be checked with addition

• Decomposition: Breaking numbers into parts to simplify calculations

Questions & Answers

Question: Why do we watch videos to learn subtraction? Can't I just listen to my teacher?

Answer: Videos are a great addition to teacher instruction! Here's why:

  • Visual Demonstrations: You can see the steps happen in real-time
  • Repetition: Watch the same video multiple times to understand better
  • Self-Paced Learning: Pause, rewind, and practice at your own speed
  • Multi-Sensory Learning: See and hear the math being done
  • Extra Practice: Use videos for additional practice at home

Videos work together with teacher instruction to help you learn better!

Question: My child watches the subtraction videos but doesn't seem to remember the strategies. How can I help?

Answer: Here are strategies to help your child retain video learning:

  • Active Viewing: Have your child pause videos to practice strategies
  • Note Taking: Encourage them to write down key steps
  • Repetition: Watch the same video multiple times
  • Hands-On Practice: Use manipulatives while watching
  • Discussion: Talk about what they learned after watching
  • Application: Have them solve similar problems immediately after

The key is active engagement, not passive watching!

Question: What if I don't understand the video? Can I skip it?

Answer: It's okay if you don't understand a video right away! Here's what to do:

  • Re-watch: Watch the video again - it often helps!
  • Pause and Think: Stop and try the strategy yourself
  • Ask for Help: Tell your teacher or parent about what's confusing
  • Try Different Videos: Watch other videos about the same topic
  • Take Notes: Write down what you don't understand
  • Practice: Try problems even if you're not sure

Learning takes time - keep trying and asking questions!