Adding and Subtracting Within 20
This unit plan will provide you with tools and resources to teach your homeschooler strategies for adding and subtracting within 20. They will learn to recognize and use the relationship between addition and subtraction to solve problems. They will also practice determining missing numbers in equations and writing fact families.
From counting money to measuring ingredients, understanding addition and subtraction is essential for practical problem-solving. By teaching your child these skills, you are equipping them with the tools they need to navigate the world confidently.
One of the key concepts in developing fluency in adding and subtracting within 20 is recognizing the relationship between the two operations. Addition and subtraction are inverse operations, meaning they undo each other.
For example, we can use the addition sentence 2 + 3 = 5 to represent combining 2 apples with 3 apples into a group of 5 apples. The opposite operation would be removing 2 apples from the group of 5 apples and leaving 3 apples. We can represent that scenario with a subtraction sentence: 5 - 2 = 3.
The relationship between addition and subtraction can also be demonstrated with related facts. Related facts are pairs of addition and subtraction equations that share the same numbers. They are also called fact families.
By teaching your child to write related facts, they can develop a deeper understanding of the connection between addition and subtraction. For example, if you know that 3 + 4 = 7, you can write the related facts 7 - 4 = 3 and 7 - 3 = 4. Encourage your child to explore these relationships and practice writing related facts to reinforce their understanding.
Another important skill is being able to determine the missing numbers in equations, also known as number sentences. For example, if you have the equation 3 + _ = 5, what number should be placed in the blank? By teaching your child strategies such as counting on, counting back, and using manipulatives, they can develop the ability to solve these types of equations with ease.
The activities in this unit will help your learner develop the following skills:
Before beginning the lessons, your learner should have a basic understanding of addition, subtraction, and number sentences. They should also be able to proficiently count and write up to 20.
By developing fluency, your child will be able to solve problems accurately and efficiently. There are various strategies you can teach your child to help them develop this fluency, such as counting on, counting back, using doubles, near doubles, making ten facts, bridging through ten, and think addition for subtraction.
Counting on and counting back are strategies that help children add and subtract small numbers, particularly 0, 1, 2, and 3. When counting on, your child starts with the larger number and counts up from there. For example, to solve 14 + 2, they would start with 14 and count 15, 16. Counting back is the opposite, where your child starts with the larger number and counts backward. For example, to solve 14 - 2, they would start with 14 and count 13, 12.
Doubles are numbers that are added to or subtracted from themselves. For example, 8 + 8 = 16 and 16 - 8 = 8. Teaching your child to recognize doubles can help them quickly solve addition and subtraction problems. Encourage them to practice doubling numbers and reinforce this strategy through games and visual aids.
Near doubles are numbers that are close to doubles, differing only by one. For example, 3 + 4 is a near double of 3 + 3. By recognizing near doubles, your child can simplify addition and subtraction problems. Provide them with opportunities to practice this strategy through hands-on activities and word problems.
Making ten involves adding numbers to make a sum of ten. Recognizing combinations that make 10, such as 7 + 3 or 8 + 2, helps children develop mental math strategies that can be applied to larger numbers. This skill helps them break down complex problems into simpler parts, building their confidence and fluency.
Bridging through ten involves adding or subtracting numbers by decomposing them into combinations that make ten. For example, to solve 9 + 6, your child can think of it as 9 + 1 + 5 = 15. By using this strategy, your child can break down complex addition and subtraction problems into smaller, more manageable steps.
Think addition is a strategy where your child solves subtraction problems using related addition facts. For example, instead of subtracting 5 from 9, they can think, "What number plus 5 equals 9?" By reframing subtraction problems as addition problems, your child can develop a deeper understanding of the relationship between the two operations.
As your child develops fluency with adding and subtracting within 20, they will begin to select strategies that work best for them. Encourage them to explore various strategies and practice using them in different contexts. By allowing your child to choose efficient strategies, they will become more confident and proficient in solving basic addition and subtraction problems.
Now that we have discussed goals and strategies, let’s explore step-by-step lessons for teaching about adding and subtracting within 20. This unit plan can be taught over several days, weeks, or longer depending on your learner’s needs.
5. Fluency Practice (Duration: 20 minutes):
Teaching your child strategies for adding and subtracting within 20 is an essential part of their mathematical development. By recognizing the relationship between addition and subtraction, determining missing numbers in equations, writing related facts, and developing fluency in basic arithmetic, your child will gain the skills they need to excel in math.
Hi, I'm Mia!
With over 12 years of experience as a classroom teacher, tutor, and homeschool parent, my specialty is easing math anxiety for students of all ages. I'm committed to empowering parents to confidently support their children in math!