How to Add and Subtract Negative Numbers With Ease
Mathnasium tutors share clear core rules, visual number lines, quick shortcuts, and practice problems to make adding and subtracting negative numbers easy.
At Mathnasium of Redondo Beach, families often come to us with concerns about their child falling behind in algebra. Your first instinct may be to have your student spend more time on current algebra topics. In our experience, though, extra practice on the same material does not always solve the problem.
That’s because algebra builds on earlier skills. Math gaps can stay hidden through elementary or middle school, then become much more noticeable once algebra asks your child to use those skills in more complex ways. That can leave a learner who once felt capable suddenly getting stuck.
Today, our education specialists will walk you through the foundational skills algebra depends on, simple ways to look for gaps at home, and practical steps you can take to help your child rebuild those skills and move forward in algebra.
By the time your child reaches Algebra as a formal course, they are already expected to draw on algebra concepts and other math knowledge built over several years. Earlier skills start working together more closely, so one shaky area can start affecting several Algebra topics at once.
Here, we use “algebra” for the ideas and skills students develop over time, and “Algebra” for the course itself.
California’s Mathematics Framework (California Department of Education, 2023), which guides Redondo Beach Unified School District (RUSD), lays out this K–12 progression. The standards build from grade to grade, so much of the groundwork for Algebra is developed well before the course begins.
Instead of treating an algebra setback as one broad issue, you can trace it back to the earlier skill your student may need to revisit. Use this table to connect Algebra topics with the foundations they depend on.
|
Algebra concept |
Foundational skill |
How the Algebra concept depends on the skill |
|
Equations and expressions |
Your child needs to undo operations in the right order, combine numerical parts accurately, work with fractional coefficients and constants, and keep equivalent expressions balanced while isolating a variable. |
|
|
Linear relationships and graphs |
- Ratios and proportions - Rate - Fractions |
Your learner uses proportional reasoning to make sense of slope, fractions to interpret rates, and coordinate skills to connect a numerical relationship with its graph. |
|
Systems of equations |
- Multi-step equations - Graphing |
Work with systems of equations builds on single-equation solving and coordinate graphing skills. |
|
Exponents and polynomials |
- Integer operations - Repeated multiplication - Order of operations - Area models - Combining like terms |
Your child draws on repeated multiplication to understand powers, integer rules to handle signs, the distributive property and like terms to expand and simplify polynomial expressions, and area models to visualize how polynomial factors combine. |
|
- Area, perimeter, volume - Angle relationships - Coordinate plane |
Your student needs to understand how geometric quantities relate before they can use variables in formulas, solve for missing dimensions, interpret coordinates, or connect equations with geometric figures. |
As long as you know which skills algebra depends on, you may find out which one might be behind your child’s algebra struggles.
These gaps tend to cluster around a certain set of areas. The National Mathematics Advisory Panel (2008) calls these the “Critical Foundations of Algebra.” They include:
Proficiency with whole numbers.
Proficiency with fractions and rational numbers.
Particular aspects of geometry and measurement, including similar triangles, perimeter, area, and volume.
To help you spot possible gaps in these areas, our education specialists put together the table below with practical ways to check each skill at home.
The activities follow the same logic as the diagnostic assessment we use at Mathnasium to pinpoint each student’s specific needs. From there, we build a personalized learning plan around the skills that require the most attention.
|
Earlier math skill |
At-home check |
What to look for in the response |
|
Whole-number fluency |
Start with a few quick facts such as 8 × 7, 15 − 9 and 6 × 9. Have your child answer without writing out a full procedure, then explain one answer in their own words. |
See whether they hesitate for too long, count on their fingers, answer incorrectly, or need to write out the steps. These patterns may suggest that your student needs more fluency with these operations. |
|
Fraction size |
Draw a number line from 0 to 1 and let them place \(\frac{2}{3}\), \(\frac{3}{4}\), and \(\frac{5}{8}\) on it. Then, invite your student to compare the fractions and explain how they decided which is greatest. |
Watch for fractions placed in the wrong general area or explanations based only on numerator and denominator size. That may mean fraction sense needs support. |
|
Fraction operations |
Give your learner \(\frac{1}{2} + \frac{1}{4}\) and \(\frac{2}{3} - \frac{1}{2}\). After they solve each one, ask them to explain why a common denominator is needed. |
If they add numerators and denominators straight across, or cannot explain the role of the denominator, they may be relying on procedures rather than truly grasp the concept. |
|
Show your child 0.5, 50%, and \(\frac{1}{2}\), then ask whether they represent the same value. Follow with 25% and have them write it as a decimal and fraction. |
Confusion between the forms, especially when they treat them as unrelated values, may point to gaps in rational-number understanding. |
|
|
Integer operations |
Try a small set such as -3+5, −4−2, and 6−9. Before calculating, let your student predict whether each answer will be positive or negative and explain why. |
Inconsistent sign choices, or relying on a rule they cannot explain can signal that integer operations are not fully settled yet. |
|
Proportional reasoning (ratios, rates) |
Tell your learner that 3 apples cost $2. Ask for the cost of 6 apples and then 9 apples, and ask them to explain how the quantities change together. |
If they can scale one quantity but lose the relationship between both, they may need more practice with ratios and rates. |
|
Area and perimeter formulas |
Give them a rectangle that is 5 units by 3 units. Have them find both the area and perimeter, then explain what each result measures. |
When the formulas are in place but your child doesn’t see the difference between covering a region and measuring around it. This may mean the underlying concept is not secure. |
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According to the IES Practice Guide, students benefit more from math help that addresses the specific skill causing the difficulty than from general instruction.
This aligns with what we do at Mathnasium. We use the diagnostic assessment to understand each student’s starting point, then build a personalized learning plan around the skills they need most. Our tutors adjust the pace and instruction as the learner progresses instead of moving every student through the same fixed set of review material.
You can try a similar approach at home with the six research-backed strategies that reflect the kind of focused support we provide at Mathnasium.
Earlier math concepts your child has not fully mastered, as well as new Algebra topics, can feel much more manageable when they see a complete example before trying it alone.
Start by working through one problem together and talking through what each step does. Then let your child take over more of the process as they become ready.
Barbieri et al’s (2023) meta-analysis found that worked examples have a positive effect on math learning.
Here’s how you can put this into practice:
Go through the worked solution to 2x + 5 = 13 together with your learner.
Then, work through the first few steps of a similar problem together: 2x + 3 = 9.
Next, give them another equation, such as 3x + 4 = 16, to solve on their own and have them talk you through the process.
Avoid showing your child one example and then expecting them to work independently right away.
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Your student can build a more solid understanding of a math topic by seeing the same idea in several forms, from concrete and visual models to the abstract symbols used in algebra.
This idea is supported by Brenner et al.’s research, which reported that students showed better problem-solving skills and transfer when instruction connected verbal, tabular, graphical, and symbolic forms rather than relying on a single representation.
For example, help your learner see the same ratio in several forms:
Physical model: Use 3 red blocks for every 2 blue blocks and build equivalent groups, such as 6 red to 4 blue and 9 red to 6 blue.
Visual: Draw a ratio table or double number line showing 3 ÷ 2, 6 ÷ 4, and 9 ÷ 6.
Symbolic: Write the equivalent ratios as \(\Large\frac{3}{2} = \Large\frac{6}{4} = \Large\frac{9}{6}\), then connect the constant ratio to a proportional relationship.
Graphical: Plot the pairs (3,2), (6,4), and (9,6) on a coordinate plane and notice that they follow the same straight-line pattern.
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When your child talks through each step, they can deepen their understanding and often catch mistakes on their own.
Ritte-Johnson et al. backed this approach in their 2017 study, where self-explanation was linked to gains in both conceptual understanding and procedural skills.
Our tutors also regularly ask learners to break down their reasoning in words during sessions.
In practice, this might look like this:
Say your student needs to compare these fractions, \(\Large\frac{7}{10}\) and \(\Large\frac{3}{4}\). Rather than asking only which fraction is greater, our tutors would ask them to explain two different ways they could compare the fractions. They might use benchmark fractions, or create equivalent fractions, place them on a number line, or convert them to decimals. Then we would ask which method felt clearest and why.
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Include several familiar problem types in the same review session. This gives your learner practice deciding which strategy each problem calls for and can make mixed-topic tests feel less unpredictable.
We can see evidence for the effectiveness of this strategy in the Rohrer et al.’s classroom study of 7th graders. It revealed that students who practiced mixed problem types scored about twice as high on a later test as students who practiced one type at a time.
You may use a mixed set like this to plan a review session:
2x + 5 = 13
\(\Large\frac{1}{2} + \Large\frac{1}{4}\) = ?
−3 + 5 = ?
8 × 7 = ?
Short practice sessions spread across the week can help your learner recall basic facts and procedures more automatically. Once those skills require less effort, your child has more mental space for the more complex algebra work that depends on them.
According to the 2006 research by Cepeda et al., spaced practice led to better long-term retention than the same amount of practice completed in one sitting.
We suggest a simple 10-minute routine across the week:
Monday: Multiplication facts, such as 6s, 7s, and 8s.
Tuesday: Fraction-decimal conversions, including \(\Large\frac{1}{2}\) = 0.5, \(\Large\frac{1}{4}\) = 0.25, and \(\Large\frac{3}{4}\) = 0.75.
Wednesday: Integer operations, like −3 + 5 and -4 − 2.
Thursday: Two-digit addition and subtraction with regrouping, for example, 47 + 38 or 62 − 27.
Friday: A mixed review using problems from earlier in the week.
Make sure your child understands why a method works before asking them to perform it faster or from memory.
Your child should stay appropriately challenged. This means they should not spend too long reviewing what they’ve already mastered or rush into what they’re not ready for.
At Mathnasium, we track each learner’s progress from session to session. Once our tutors see that a skill is holding up consistently, we move on to the next step. If the student still needs support, we stay with that skill a little longer and adjust the instruction.
Here is how this works:
Your learner solves two-step equations accurately across several sessions and can explain the process. We may then introduce a related next step, such as more complex equations, instead of assigning another batch of the same problems.
The concept is still shaky? We spend some more time with two-step equations before adding another layer of difficulty.
If you find it hard to pinpoint or address the math gaps behind your child’s algebra struggles, our algebra tutors at Mathnasium of Redondo Beach would be happy to help!

Mathnasium tutors use different teaching techniques and hands-on activities to help learners master the skills algebra builds on.
Mathnasium of Redondo Beach is a math-only learning center dedicated to helping K–12 students of all skill levels excel in math. We help students make sense of any math concept, so they can carry that understanding into more advanced math with greater confidence.
To do that, we use the Mathnasium Method™, our proprietary teaching approach, to meet students where they are and guide them forward step by step.
Every student begins with a diagnostic assessment that helps us understand their current skill level, knowledge gaps, goals, and how they think and feel about math. This helps us look beyond the current algebra grade and identify which earlier skills may be making the work harder.
Using these insights, we build a personalized learning plan focused on the skills the student needs most, whether that means revisiting fraction operations, working more accurately with signed numbers, making sense of equations, or reinforcing other foundations that Algebra 1 depends on.
Our specially trained tutors follow that plan closely and provide live, face-to-face instruction in a caring and fun group environment. They use mental, verbal, visual, tactile, and written techniques to help students connect algebraic procedures to the ideas behind them.
Students also get room to think through problems before tutors step in. Our tutors guide them through the problem rather than simply giving the correct answer. This helps students develop the critical thinking, problem-solving skills, and independence they need in algebra and later math.
Fun is part of the approach, too. We use game-based activities, rewards, and consistent encouragement to keep students engaged as they revisit earlier skills and work through more challenging algebra concepts.
The impact is clear in our results:
94% of parents report an improvement in their child's math skills and understanding
93% of parents report their child's improved attitude toward math after attending Mathnasium
90% of students saw an improvement in their school grades
If your child falls behind in algebra, a free diagnostic assessment is a great place to start. Using what we learn, we create a personalized learning plan focused on the specific skills they need next.
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Our specially trained tutors deliver face-to-face instruction in a supportive and fun small-group environment, working with students to develop a deep understanding of math, build confidence, and improve academic performance.
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