Subtraction Or Addition

Grade 1: Common Core Mathematics Standard

CCSS.MATH.CONTENT.1.OA.B.4
Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.

Addition Versus Subtraction
I've seen many people struggle with the connection between addition and subtraction. Most people find addition to be easier and they prefer to use it whenever they can. They see subtraction as "scary". If you understand the relationship between addition and subtraction then you can use addition to make subtracting easier. 

Video

There's no need to be afraid of doing subtraction if you understand its relationship with addition. They are like best friends. They compliment each other. If you need to find the answer to a subtraction problem it is much easier to do so when you use addition to find the missing addend. 

You can even represent the numbers with dots or other pictures to get a better understanding of how to find the missing number. You're still thinking about the family and how many more dots you need to get to the total but having a visual may help you understand better. I personally like drawing out my numbers if they're small enough. 
Practice Problems

Problem 1: What is 15-3? What three numbers make up this "family" 15, 3, and __? Demonstrate how we would use addition to find the missing addend and explain how you did it. If you need help, look back at my video above. 

Problem 2: What is 7-2? What three numbers make up this family? Demonstrate how we would use addition to find the missing addend and explain how you did it. If you need help, refer to my video.

Questions to Consider...

• Is using addition helpful for you when solving subtraction problems?
• Does the use of dots make the problems easier for you?
• What other ways are there to make subtracting easier?

Other Sites and Games to Help you

https://www.youtube.com/watch?v=aK3FKEZJKec

https://mathgeekmama.com/fact-family-games/

Fractions in Shapes

Grade 1: Common Core Mathematics Standard:

CCSS.MATH.CONTENT.1.G.A.3
Partition circles and rectangles into two and four equal shares, describe the shares using the words halves, fourths, and quarters, and use the phrases half of, fourth of, and quarter of. Describe the whole as two of, or four of the shares. Understand for these examples that decomposing into more equal shares creates smaller shares.

Fractions

It may be confusing for some students to understand what pieces or fractions of a shape are smaller or larger.  So, today I am going to cover how to divide a rectangle or circle into two equal parts and four equal parts. The pictures I will be using will help me show you which fractions are larger. I will also show you how to represent the pieces of shapes as fractions by using numbers. 

Video

Rectangles work the same way, in the picture below there are three rectangles. They are the same size but with different shares drawn on them. This is to show you that shapes can be split into the same number of shares in different ways. Two of the rectangles are split into halves (two pieces). Those are two different ways that the rectangle could be cut in half but they still represent the same amounts. The bottom rectangle is split into quarters or fourths (four pieces). The two pieces in both of the top two rectangles are the same. The four pieces within the bottom rectangle are the same. However, the pieces in the bottom rectangle are smaller. The size of the rectangle did not change but the amount of pieces that we made did, so the pieces have to be smaller so there can be more of them. Now there are just more parts of the same whole shape.



Main Idea:
 It may seem that just because there are more pieces, there is more to give away. But, more pieces means less space in each. If you compare the circle with two pieces to the circle with four pieces, you can tell that the circle stayed the same size but each piece has less space in it to give away.

Practice Problem

Now that you have learned how to tell the difference between halves and quarters, look at these pictures of squares and draw them out on a piece of paper. 


Which square is in halves? Label each piece with 1/2.
Which square is in quarters? Label each piece with 1/4.
If you gave away a one piece of the white square to your mom and a piece of the green square away to your dad, who would have the bigger piece and why?

Other Sites and Games to Help You

https://www.iknowit.com/lessons/b-fractions-equal-parts.html

https://www.homeschoolmath.net/teaching/f/understanding_fractions.php




Images obtained from: 
https://www.iconfinder.com/icons/4998333/geometric_half_highlight_shape_square_icon
https://www.homeschoolmath.net/teaching/f/understanding_fractions.php