MATHCOUNTS provides many free problem sets, videos, lesson plans and activities that can complement in-person and online learning. We've categorized some of the best resources for several middle school math topics:

• Arithmetic Skills
• Introduction to Counting
• Basic Number Sense
• Exploring Equations
• Properties of Right Triangles
• Multiple Approaches to Problems
• Squares
• Using Similar Figures
• Area and Perimeter
• Sequences, Series and Patterns (Part 1)
• Sequences, Series and Patterns (Part 2)
• Probability
• Circles
• Rates and Proportional Reasoning

Arithmetic Skills
Faster Arithmetic Models
Practice Plan

Using the commutative, associative and distributive properties, Mathletes will arrange arithmetic problems in a different order that allows them to be solved more readily.

Order of Operations and Defining New Rules
Practice Plan

After refreshing Mathletes on the order of operations, the video will then focus on how to solve problems where an unfamiliar symbol is defined to be a new type of operations that follows given rules.

The Multiplication Game
National Math Club Game

In The Multiplication Game players take turns chosing factors to obtain a product on the game board. The first player to four squares in a row wins. The game can be used to practice multiplication tables and factor pairs as well as to discuss prime and composite numbers.

Salute
National Math Club Game

In a heads up style game, students use inverse operations to guess the card on their forehead. They may or may not realize they are doing algebra! Register for the free National Math Club to access this game and dozens of others!

A-maze-ing Fractions
National Math Club Exploration

Operations with fractions are often hard for students to conceptualize. With this exploration's dry erase maze boards and four basic arithmetic operations, Mathletes can begin to uncover the secrets of fractions by finding a path that results in the least value or the greatest value. Register for the free National Math Club to access this activity and dozens of others!

Counting Bee
National Math Club Game

Help students improve their basic arithmetic skills by competing in a club counting bee. Given a starting number and counting number, see how far students can count in 15 seconds! Register for the free National Math Club to access this game and dozens of others!

Introduction to Counting
Counting Shapes in a Complex Figure
Practice Plan

This plan will help Mathletes to develop a strategic approach to counting the occurrences of a certain shape in a more complex figure made of multiple intersecting lines.

Counting Paths Along a Grid
Practice Plan

Explore combinatorics by looking at a common type of MATHCOUNTS counting problem – counting paths between two points. End with an extension that connects counting paths to another type of combinatoric problem.

The Fundamental Counting Principle
Practice Plan

This plan will introduce students to The Fundamental Counting Principle – a faster method to determining the total number of possible outcomes of an event without listing them all out!

Counting Possibilities
MATHCOUNTS Mini

This video focuses on using diagrams and organized lists to ensure that each possible outcome is counted once, and only once.

Constructive Counting
MATHCOUNTS Mini

Moving beyond the fundamental counting principle, students will be introduced to the difference between combinations and permutations, and presented with multiple methods for solving these types of problems.

Counting & Combinatorics Stretch
Problem Set

Two sets of ten practice problems from the 2002-2003 and 2015-2016 MATHCOUNTS School Handbook that cover basic counting including some number sense, shapes and paths.

Basic Number Sense
Divisibility Rules
Practice Plan

Students will apply divisibility rules of various integers to simplify computation, better understand number composition and aid in problem solving. In the extension, Mathletes can prove why each of these rules work!

Least Common Multiple
Practice Plan

Calculating the least common multiple is something many students are asked to do, but in this plan they will use their understanding of the least common multiple to stretch themselves to solve more complex problems.

Marble Challenge
National Math Club Game

In the Marble Challenge students will take turns removing marbles with the goal of not taking the last marble. This game encourages students to notice patterns in the numbers and can even be used to introduce modular arithmetic. Register for the free National Math Club to access this game and dozens of others!

Ken Ken
National Math Club Exploration

Using increasingly popular KenKen® puzzles, Mathletes will use teamwork, number sense and logic skills to solve challenges. Register for the free National Math Club to access this activity and dozens of others!

Strategic Guessing Using Divisibility Rules
MATHCOUNTS Mini

Often in MATHCOUNTS you find yourself with a unique problem you don't already have a prescribed method for solving. This mini gives examples of such problems that can be solved with a little logic, number sense and understanding of divisibility rules.

Number Sense Stretches
Problem Sets

In these number sense stretches, there are three problem sets (10 problems each) from old MATHCOUNTS School Handbooks that covers number sense topics such as factoring and divisibility. These are great additional practice in after trying the Practice Plans and MATHCOUNTS Minis.

Exploring Equations
You Don't Have to Solve for x!
Practice Plan

Often the immediate reaction when Mathletes see an algebraic equation is to solve for the unknown but depending on what you are looking for it might be easier to manipulate the equation without solving it.

Mathemagicians
National Math Club Exploration

This exploration is a great way to practice translating word problems into algebraic equations and to develop understanding of the concept of inverse operations. Mathletes will be amazed at first by what appears to be magic, but they will come to understand that the tricks can be explained using algebra. Mathletes can come up with their own magic examples to impress their friends and families and become true mathemagicians! Register for the free National Math Club to access this activity and dozens of others!

Function Battleship
National Math Club Exploration

This exploration lets Mathletes manipulate functions in order to explore and better understand translating, stretching, compressing and other transformations of functions. Through the Desmos platform, with the added twist of similarity to the board game Battleship, Mathletes can graph functions and see the effects of changing coefficients and exponents and adding and subtracting integers. Register for the free National Math Club to access this activity and dozens of others!

Salute
National Math Club Game

In a heads up style game, students use inverse operations to guess the card on their forehead. They may or may not realize they are doing algebra! Register for the free National Math Club to access this game and dozens of others!

Algebraic Equations from Word Problems
MATHCOUNTS Mini

These problems and video focus on translanting the information in word problems into representative algebraic equations.

Seeing Symmetry in Systems of Equations
MATHCOUNTS Mini

When dealing with systems of equations, if you are able to recognize symmetry between the equations, you can simplify the steps to a solution. This Mini will look at some problems and demonstrate how to find and use the symmetry to your advantage.

Properties of Right Triangles
Special Right Triangles
Practice Plan

Mathletes will become familiar with properties of 45-45-90 and 30-60-90 triangles. In this plan, the relationships between the sides of these two special right triangles will be derived. Then, Mathletes will apply these to solve for unknown lengths in geometric figures.

Right Triangles
MATHCOUNTS Mini

From special right triangles to Pythagorean Triples, this video shows how to use properties of right triangles to solve problems.

Proofigami
National Math Club Exploration

This exploration gives Mathletes a brief introduction of the Pythagorean Theorem, then guides them through what we call Proofigami. This fun exploration will feel a lot like origami, but will provide Mathletes with a better understanding of the Pythagorean Theorem and gives club leaders a visual and tactile tool that makes explaining this proof easier. Register for the free National Math Club to access this activity and dozens of others!

30-60-90 Right Triangles
MATHCOUNTS Mini

This MATHCOUNTS Mini will look at ways to use known ratios of 30-60-90 triangles to help solve more complex geometric problems.

Right Triangles Stretch
Problem Set

Practice solving problems by using the Pythagorean Theorem, recognizing Pythagorean triples and applying properties of special right triangles.

Trapezoids and Triangles
MATHCOUNTS Mini

This video explores how we can decompose a figure into trapezoids and triangles to determine its area. The problems associated with this mini will help students determine when and how to apply their right triangle knowledge to solve more complex geometry problems.

Multiple Approaches to Problems
More Than One Way to Solve a Problem
MATHCOUNTS Mini

This video demonstrates multiple problem-solving strategies and emphasizes the importance of solving problems in more than one way to verify that you've solved a problem correctly.

Even More Than One Way to Solve a Problem
MATHCOUNTS Mini

This video reinforces the concept of solving a problem multiple ways to validate your answer.

Fun Problem-Solving Techniques
National Math Club Problem Set

Being able to take multiple different approaches to solve problems is an invaluable skill. In this problem set, students will look at four techniques - creating a model, acting out a situation, drawing a picture and making a list.

Three Tic-Tac-Toes
National Math Club Game

Chances are students are familiar with tic-tac-toe, but these rule variants on the traditional version will challenge students to rethink their strategy. Use this game to talk about symmetry, logic and proof writing.

Draw a Picture
MATHCOUNTS Mini

This video explores how to solve problems by drawing a picture to organize the given information.

Make a Sketch
MATHCOUNTS Mini

This video demonstrates how making a sketch of a given scenario can be a useful strategy when solving problems.

Squares
Recognizing Squares and Solving a Simpler Problem
MATHCOUNTS Mini

This video focuses on recognizing squares and using them to solve a simpler problem.

Using the Difference of Squares to Solve Problems
MATHCOUNTS Mini

This video explores how to use the difference of squares to solve problems and why this method works.

Systems of Equations Stretch
Problem Set

Apply the difference of squares formula in order to solve problems involving systems of equations.

Difference of Squares
Practice Plan

An important formula to know, the difference of squares identity is derived geometrically in the video for this problem set. Mathletes will then try to recognize the difference of squares structure in various expressions and use the identity to find the value.

Perfect Squares/Using a Simpler Case to Solve a Problem
MATHCOUNTS Mini

This video demonstrates how to use perfect squares to find a simpler case to help solve a problem.

Difference of Squares
MATHCOUNTS Mini

This video demonstrates how to solve problems using the difference of squares.

Using Similar Figures
Similar Triangles and Proportional Reasoning
MATHCOUNTS Mini

This video shows how to identify and use similar triangles to solve geometry problems.

Using Similarity to Solve Geometry Problems
MATHCOUNTS Mini

This video explores how to apply properties of similar triangles in solving problems about two-dimensional and three-dimensional figures.

Similarity and Proportional Reasoning Stretches
Problem Sets

Practice with the concept of similarity by answering questions about similar figures, and see how similarity relates to proportional reasoning and geometric transformations.

Using Similarity to Solve Geometry Problems
MATHCOUNTS Mini

This video demonstrates how to use similarity and proportional reasoning to solve difficult geometry problems.

Similarity and Proportional Reasoning
MATHCOUNTS Mini

Sometimes it is necessary to create the similar triangles you'll need in order to solve a problem. This video shows how to look at and build on given diagrams to create similar figures.

Similar Triangles
MATHCOUNTS Mini

This video explores how to use parallel lines and angles to identify similar triangles and solve problems.

Area and Perimeter
Fence Me In
National Math Club Game

After rolling dice to determine the size, in part, of a rectangle, players then use perimeter and area formulas to determine dimensions. The goal is to try to fill up the board first.

Areas of Irregular Convex Polygons
MATHCOUNTS Mini

This video demonstrates two strategies for how to find the area of an irregular convex polygon.

Geometry Stretches
Problem Sets

Find the areas and perimeters of various figures, and see how area and perimeter measurements can be used to solve other types of geometry problems.

Area of Irregular Polygons Reboot
MATHCOUNTS Mini

This video demonstrates how to find the area of an irregular polygon by dividing the figure into smaller regions for which the area is more easily determined.

Trapezoids and Triangles
MATHCOUNTS Mini

This video explores how we can decompose a figure into trapezoids and triangles to determine its area.

Shamrock
Problem of the Week

Practice calculating area and perimeter measurements using the image of a shamrock.

Sequences, Series and Patterns (Part 1)
Number Sense: Looking for Patterns
MATHCOUNTS Mini

This video focuses on techniques for solving problems by looking for patterns that emerge among the digits in large numbers.

Patterns All Around
National Math Club Game

Recognizing patterns in objects in order to express them mathematically is an important skill for students to learn. In this game students will attempt to recognize visual and numeric patterns in a group of cards.

Sequences, Series and Patterns
MATHCOUNTS Mini

This video shows how to find patterns in both visual and numerical sequences and how to use patterns to identify an unknown value in a sequence.

More Sequences, Series and Patterns
MATHCOUNTS Mini

This video demonstrates how to find a pattern in a sequence or series, and prove that it works, to solve problems.

Representing Patterns Numerically
Practice Plan

In this practice plan, Mathletes will recognize visual patterns and practice defining them numerically in order to find the number of elements in the pattern after a large number of repetitions.

Patterns Stretches
Problem Sets

Practice with patterns through problems about visual and numerical sequences and series, the digits of large numbers and other real-world and math topics.

Sequences, Series and Patterns (Part 2)
Arithmetic and Geometric Sequences
MATHCOUNTS Mini

This video explores how to solve problems about arithmetic and geometric sequences.

Relationships Between Arithmetic Sequences, Mean and Median
MATHCOUNTS Mini

This video demonstrates how to use mean and median in solving problems about arithmetic sequences.

Arithmetic Sequences
MATHCOUNTS Mini

This video focuses on techniques for solving problems involving arithmetic sequences, including finding the nth term.

Sequences Stretches
Problem Sets

Practice with standard arithmetic and geometric sequences and series, as well as with other special types of sequences and series, like the Fibonacci sequence.

Patterns, Sequences and Series
MATHCOUNTS Mini

This video shows a few techniques for solving problems using patterns in sequences and series.

Sequences and Central Tendency
MATHCOUNTS Mini

This video demonstrates how the relationship between measures of central tendency and sequences can be used to solve problems.

Probability
Ratios and Simple Probability
Practice Plan

This problem set builds on what students already know about ratios to introduce the definition of probability as a ratio of desired outcomes to total outcomes. Mathletes will then practice calculating the likelihood of single events.

Let's Make a Deal
National Math Club Exploration

For years, the Monty Hall Problem has been debated and examined. Mathletes will play the game in groups and use mathematical reasoning to decide - Do you switch? Do you NOT switch? Or is it a 50/50 chance either way?

Probability with Geometry Representations
MATHCOUNTS Mini

This video demonstrates how to solve certain probability problems using geometric representations.

Dice Duel
National Math Club Game

Players compete to roll the numbers on their product cards without rolling their opponents. They will have to use their understanding of probability to win.

Probability Stretches
Problem Sets

Practice with probability through a wide variety of probability problems from many years of MATHCOUNTS School Handbooks.

Probability Problem Solving
MATHCOUNTS Mini

This video explores some helpful strategies for approaching probability problems.

Circles
Pi Day
National Math Club Problem Set

This π-themed problem set, created to celebrate Pi Day, has problems involving π on a variety of topics, including solid geometry, plane geometry and number theory.

Circles and Area Revisited
MATHCOUNTS Mini

This video focuses on finding area using properties of circles.

Happy Pi Day
Problem of the Week

This Problem of the Week from 2009 on circles focuses on finding the areas of various regions.

Circles Stretches
Problem Sets

Practice with circles, and see how they can be used in a variety of problems to answer questions about other shapes.

Circles and Triangles Revisited
MATHCOUNTS Mini

This video explores solving problems using properties of circles and triangles.

The Value of Pi
Problem of the Week

This Problem of the Week from 2007 explores where π came from, how it was approximated and some of its many uses.

Rates and Proportional Reasoning
Distance = Rate x Time
Practice Plan

Explore the formula d = rt by starting with unit conversion problems. Mathletes will solve for distance, rate and time by paying attention to the units given in the problem and using the appropriate equivalent version of the formula: d = rt, r = d/t or t = d/r.

New Approaches to Rate x Time = Distance
MATHCOUNTS Mini

This video desmonstrates some alternative approaches to problems traditionally solved by using d = rt.

Algebra Rates
MATHCOUNTS Mini

This video explores algebra rate problems, using a variety of problem-solving techniques.

Rates and Proportional Reasoning Stretches
Problem Sets

Practice with rates and proportional reasoning through a wide variety of problems from many years of MATHCOUNTS School Handbooks.

It's Marathon Season
Problem of the Week

Using marathon statistics, practice applying the formula d = rt and equivalent versions in this 2001 Problem of the Week.

Indianapolis 500
Problem of the Week

Practice with rates and proportional reasoning in this 2007 Problem of the Week using some statistics from the Indianapolis 500 race.