### Quick, easy, and fun interactive math explorations

GeoGebra is interactive and challenging, but kids might get frustrated and give up if they don't get clear directions.

Kids create their own understanding by building and modifying mathematic constructions.

Available in many different languages, including English, Japanese, Spanish, and Turkish. Extensive introductory materials include video tutorials and a user forum.

GeoGebra offers kids and teachers the option of using existing math explorations or building their own. The existing pool of explorations is vast, so it covers most high school Common Core math expectations, especially those involving graphing or geometry. Activities are built and shared by anyone who wants to be an author, so quality varies greatly. Many, like "Calculating Mean, Standard Deviation, 5-Number Summary, IQR," do not provide specific directions for kids.

However, GeoGebra gives kids a way to access math that moves beyond straightforward pencil-and-paper computations. Traditional methods of performing constructions with a compass and a ruler can be time-consuming and frustrating for kids. GeoGebra makes it quick, easy, and fun as long as the kids have clear directions.

Teachers will need to spend some time with the extensive tutorials in order to familiarize themselves with the program and its capabilities. The administer tutorials provide options to let teachers incorporate GeoGebra into their existing class sites using Moodle, Wordpress, and other options.

**Standout Explorations:**

**Coordinates Game Boat** – Drag slider bars to label the coordinates and get the boat in your viewfinder.

**Create a Box and Whisker Plot** – Drag sliders to create a box and whisker plot that fits given data.

**Area of a Trapezoid by Deconstruction **– Derive the equation for the area of a trapezoid by cutting up the polygons into rectangles and triangles.

GeoGebra is a free software program that lets kids create mathematical constructions and models. They drag objects and adjust parameters to explore algebra and geometry simultaneously. GeoGebra also lets teachers make their own interactive worksheets or use free materials created by others. After you click on Download from the homepage, the site gives you the option to use WebStart or Applet Start. WebStart downloads a program using your computer, requires Java, and gives you an icon on your desktop. Applet Start is fully functional and just uses your browser window.

*Geogebra*was written by Emily Pohlonski

*Submitted November 5, 2013*

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*Submitted November 4, 2013*

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*Submitted July 19, 2013*

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*Submitted August 29, 2013*

## Key Standards Supported

## Arithmetic With Polynomials And Rational Expressions | |

HSA.APR: Understand The Relationship Between Zeros And Factors Of Polynomials | |

HSA.APR.3 | Identify zeros of polynomials when suitable factorizations are available, and use the zeros to construct a rough graph of the function defined by the polynomial. |

## Building Functions | |

HSF.BF: Build New Functions From Existing Functions | |

HSF.BF.3 | Identify the effect on the graph of replacing f(x) by f(x) + k, k f(x), f(kx), and f(x + k) for specific values of k (both positive and negative); find the value of k given the graphs. Experiment with cases and illustrate an explanation of the effects on the graph using technology. Include recognizing even and odd functions from their graphs and algebraic expressions for them. |

HSF.BF.4 | Find inverse functions. |

## Circles | |

HSG.C: Find Arc Lengths And Areas Of Sectors Of Circles | |

HSG.C.5 | Derive using similarity the fact that the length of the arc intercepted by an angle is proportional to the radius, and define the radian measure of the angle as the constant of proportionality; derive the formula for the area of a sector. |

Understand And Apply Theorems About Circles | |

HSG.C.1 | Prove that all circles are similar. |

HSG.C.2 | Identify and describe relationships among inscribed angles, radii, and chords. Include the relationship between central, inscribed, and circumscribed angles; inscribed angles on a diameter are right angles; the radius of a circle is perpendicular to the tangent where the radius intersects the circle. |

HSG.C.3 | Construct the inscribed and circumscribed circles of a triangle, and prove properties of angles for a quadrilateral inscribed in a circle. |

HSG.C.4 | (+) Construct a tangent line from a point outside a given circle to the circle. |

## Conditional Probability And The Rules Of Probability | |

HSS.CP: Understand Independence And Conditional Probability And Use Them To Interpret Data | |

HSS.CP.1 | Describe events as subsets of a sample space (the set of outcomes) using characteristics (or categories) of the outcomes, or as unions, intersections, or complements of other events (“or,” “and,” “not”). |

HSS.CP.2 | Understand that two events A and B are independent if the probability of A and B occurring together is the product of their probabilities, and use this characterization to determine if they are independent. |

HSS.CP.3 | Understand the conditional probability of A given B as P(A and B)/P(B), and interpret independence of A and B as saying that the conditional probability of A given B is the same as the probability of A, and the conditional probability of B given A is the same as the probability of B. |

Use The Rules Of Probability To Compute Probabilities Of Compound Events In A Uniform Probability Model | |

HSS.CP.6 | Find the conditional probability of A given B as the fraction of B’s outcomes that also belong to A, and interpret the answer in terms of the model. |

HSS.CP.7 | Apply the Addition Rule, P(A or B) = P(A) + P(B) – P(A and B), and interpret the answer in terms of the model. |

HSS.CP.8 | (+) Apply the general Multiplication Rule in a uniform probability model, P(A and B) = P(A)P(B|A) = P(B)P(A|B), and interpret the answer in terms of the model. |

HSS.CP.9 | (+) Use permutations and combinations to compute probabilities of compound events and solve problems. |

## Congruence | |

HSG.CO: Experiment With Transformations In The Plane | |

HSG.CO.1 | Know precise definitions of angle, circle, perpendicular line, parallel line, and line segment, based on the undefined notions of point, line, distance along a line, and distance around a circular arc. |

HSG.CO.2 | Represent transformations in the plane using, e.g., transparencies and geometry software; describe transformations as functions that take points in the plane as inputs and give other points as outputs. Compare transformations that preserve distance and angle to those that do not (e.g., translation versus horizontal stretch). |

HSG.CO.3 | Given a rectangle, parallelogram, trapezoid, or regular polygon, describe the rotations and reflections that carry it onto itself. |

HSG.CO.4 | Develop definitions of rotations, reflections, and translations in terms of angles, circles, perpendicular lines, parallel lines, and line segments. |

HSG.CO.5 | Given a geometric figure and a rotation, reflection, or translation, draw the transformed figure using, e.g., graph paper, tracing paper, or geometry software. Specify a sequence of transformations that will carry a given figure onto another. |

Make Geometric Constructions | |

HSG.CO.12 | Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, etc.). Copying a segment; copying an angle; bisecting a segment; bisecting an angle; constructing perpendicular lines, including the perpendicular bisector of a line segment; and constructing a line parallel to a given line through a point not on the line. |

HSG.CO.13 | Construct an equilateral triangle, a square, and a regular hexagon inscribed in a circle. |

Prove Geometric Theorems | |

HSG.CO.10 | Prove theorems about triangles. Theorems include: measures of interior angles of a triangle sum to 180°; base angles of isosceles triangles are congruent; the segment joining midpoints of two sides of a triangle is parallel to the third side and half the length; the medians of a triangle meet at a point. |

HSG.CO.11 | Prove theorems about parallelograms. Theorems include: opposite sides are congruent, opposite angles are congruent, the diagonals of a parallelogram bisect each other, and conversely, rectangles are parallelograms with congruent diagonals. |

HSG.CO.9 | Prove theorems about lines and angles. Theorems include: vertical angles are congruent; when a transversal crosses parallel lines, alternate interior angles are congruent and corresponding angles are congruent; points on a perpendicular bisector of a line segment are exactly those equidistant from the segment’s endpoints. |

Understand Congruence In Terms Of Rigid Motions | |

HSG.CO.6 | Use geometric descriptions of rigid motions to transform figures and to predict the effect of a given rigid motion on a given figure; given two figures, use the definition of congruence in terms of rigid motions to decide if they are congruent. |

HSG.CO.7 | Use the definition of congruence in terms of rigid motions to show that two triangles are congruent if and only if corresponding pairs of sides and corresponding pairs of angles are congruent. |

HSG.CO.8 | Explain how the criteria for triangle congruence (ASA, SAS, and SSS) follow from the definition of congruence in terms of rigid motions. |

## Creating Equations | |

HSA.CED: Create Equations That Describe Numbers Or Relationships | |

HSA.CED.2 | Create equations in two or more variables to represent relationships between quantities; graph equations on coordinate axes with labels and scales. |

## Expressing Geometric Properties With Equations | |

HSG.GPE: Translate Between The Geometric Description And The Equation For A Conic Section | |

HSG.GPE.1 | Derive the equation of a circle of given center and radius using the Pythagorean Theorem; complete the square to find the center and radius of a circle given by an equation. |

HSG.GPE.2 | Derive the equation of a parabola given a focus and directrix. |

HSG.GPE.3 | (+) Derive the equations of ellipses and hyperbolas given the foci, using the fact that the sum or difference of distances from the foci is constant. |

Use Coordinates To Prove Simple Geometric Theorems Algebraically | |

HSG.GPE.4 | Use coordinates to prove simple geometric theorems algebraically. For example, prove or disprove that a figure defined by four given points in the coordinate plane is a rectangle; prove or disprove that the point (1, √3) lies on the circle centered at the origin and containing the point (0, 2). |

HSG.GPE.5 | Prove the slope criteria for parallel and perpendicular lines and use them to solve geometric problems (e.g., find the equation of a line parallel or perpendicular to a given line that passes through a given point). |

HSG.GPE.6 | Find the point on a directed line segment between two given points that partitions the segment in a given ratio. |

HSG.GPE.7 | Use coordinates to compute perimeters of polygons and areas of triangles and rectangles, e.g., using the distance formula.★ |

## Functions | |

8.F: Define, Evaluate, And Compare Functions. | |

8.F.1 | Understand that a function is a rule that assigns to each input exactly one output. The graph of a function is the set of ordered pairs consisting of an input and the corresponding output.1 |

## Geometric Measurement And Dimension | |

HSG.GMD: Explain Volume Formulas And Use Them To Solve Problems | |

HSG.GMD.1 | Give an informal argument for the formulas for the circumference of a circle, area of a circle, volume of a cylinder, pyramid, and cone. Use dissection arguments, Cavalieri’s principle, and informal limit arguments. |

HSG.GMD.2 | (+) Give an informal argument using Cavalieri’s principle for the formulas for the volume of a sphere and other solid figures. |

HSG.GMD.3 | Use volume formulas for cylinders, pyramids, cones, and spheres to solve problems.★ |

Visualize Relationships Between Two-Dimensional And Three- Dimensional Objects | |

HSG.GMD.4 | Identify the shapes of two-dimensional cross-sections of three- dimensional objects, and identify three-dimensional objects generated by rotations of two-dimensional objects. |

## Interpreting Categorical And Quantitative Data | |

HSS.ID: Interpret Linear Models | |

HSS.ID.7 | Interpret the slope (rate of change) and the intercept (constant term) of a linear model in the context of the data. |

HSS.ID.8 | Compute (using technology) and interpret the correlation coefficient of a linear fit. |

HSS.ID.9 | Distinguish between correlation and causation. |

Summarize, Represent, And Interpret Data On A Single Count Or Measurement Variable | |

HSS.ID.1 | Represent data with plots on the real number line (dot plots, histograms, and box plots). |

HSS.ID.2 | Use statistics appropriate to the shape of the data distribution to compare center (median, mean) and spread (interquartile range, standard deviation) of two or more different data sets. |

Summarize, Represent, And Interpret Data On Two Categorical And Quantitative Variables | |

HSS.ID.5 | Summarize categorical data for two categories in two-way frequency tables. Interpret relative frequencies in the context of the data (including joint, marginal, and conditional relative frequencies). Recognize possible associations and trends in the data. |

HSS.ID.6 | Represent data on two quantitative variables on a scatter plot, and describe how the variables are related. |

## Interpreting Functions | |

HSF.IF: Analyze Functions Using Different Representations | |

HSF.IF.7 | Graph functions expressed symbolically and show key features of the graph, by hand in simple cases and using technology for more complicated cases.★ |

HSF.IF.8 | Write a function defined by an expression in different but equivalent forms to reveal and explain different properties of the function. |

HSF.IF.9 | Compare properties of two functions each represented in a different way (algebraically, graphically, numerically in tables, or by verbal descriptions). For example, given a graph of one quadratic function and an algebraic expression for another, say which has the larger maximum. |

Interpret Functions That Arise In Applications In Terms Of The Context | |

HSF.IF.4 | For a function that models a relationship between two quantities, interpret key features of graphs and tables in terms of the quantities, and sketch graphs showing key features given a verbal description of the relationship. Key features include: intercepts; intervals where the function is increasing, decreasing, positive, or negative; relative maximums and minimums; symmetries; end behavior; and periodicity.★ |

HSF.IF.5 | Relate the domain of a function to its graph and, where applicable, to the quantitative relationship it describes. For example, if the function h(n) gives the number of person-hours it takes to assemble n engines in a factory, then the positive integers would be an appropriate domain for the function.★ |

HSF.IF.6 | Calculate and interpret the average rate of change of a function (presented symbolically or as a table) over a specified interval. Estimate the rate of change from a graph.★ |

## Linear, Quadratic, And Exponential Models | |

HSF.LE: Construct And Compare Linear, Quadratic, And Exponential Models And Solve Problems | |

HSF.LE.1 | Distinguish between situations that can be modeled with linear functions and with exponential functions. |

HSF.LE.2 | Construct linear and exponential functions, including arithmetic and geometric sequences, given a graph, a description of a relationship, or two input-output pairs (include reading these from a table). |

HSF.LE.3 | Observe using graphs and tables that a quantity increasing exponentially eventually exceeds a quantity increasing linearly, quadratically, or (more generally) as a polynomial function. |

HSF.LE.4 | For exponential models, express as a logarithm the solution to abct =dwherea,c,anddarenumbersandthebasebis2,10,ore; evaluate the logarithm using technology. |

## Reasoning With Equations And Inequalities | |

HSA.REI: Represent And Solve Equations And Inequalities Graphically | |

HSA.REI.10 | Understand that the graph of an equation in two variables is the set of all its solutions plotted in the coordinate plane, often forming a curve (which could be a line). |

HSA.REI.11 | Explain why the x-coordinates of the points where the graphs of the equations y = f(x) and y = g(x) intersect are the solutions of the equation f(x) = g(x); find the solutions approximately, e.g., using technology to graph the functions, make tables of values, or find successive approximations. Include cases where f(x) and/or g(x) are linear, polynomial, rational, absolute value, exponential, and logarithmic functions.★ |

HSA.REI.12 | Graph the solutions to a linear inequality in two variables as a half- plane (excluding the boundary in the case of a strict inequality), and graph the solution set to a system of linear inequalities in two variables as the intersection of the corresponding half-planes. |

Solve Systems Of Equations | |

HSA.REI.6 | Solve systems of linear equations exactly and approximately (e.g., with graphs), focusing on pairs of linear equations in two variables. |

HSA.REI.7 | Solve a simple system consisting of a linear equation and a quadratic equation in two variables algebraically and graphically. For example, find the points of intersection between the line y = –3x and the circle x2 + y2 = 3. |

HSA.REI.8 | (+) Represent a system of linear equations as a single matrix equation in a vector variable. |

HSA.REI.9 | (+) Find the inverse of a matrix if it exists and use it to solve systems of linear equations (using technology for matrices of dimension 3 × 3 or greater). |

## Similarity, Right Triangles, And Trigonometry | |

HSG.SRT: Apply Trigonometry To General Triangles | |

HSG.SRT.10 | (+) Prove the Laws of Sines and Cosines and use them to solve problems. |

HSG.SRT.11 | (+) Understand and apply the Law of Sines and the Law of Cosines to find unknown measurements in right and non-right triangles (e.g., surveying problems, resultant forces). |

HSG.SRT.9 | (+) Derive the formula A = 1/2 ab sin(C) for the area of a triangle by drawing an auxiliary line from a vertex perpendicular to the opposite side. |

Define Trigonometric Ratios And Solve Problems Involving Right Triangles | |

HSG.SRT.6 | Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles. |

HSG.SRT.7 | Explain and use the relationship between the sine and cosine of complementary angles. |

HSG.SRT.8 | Use trigonometric ratios and the Pythagorean Theorem to solve right triangles in applied problems.★ |

Prove Theorems Involving Similarity | |

HSG.SRT.4 | Prove theorems about triangles. Theorems include: a line parallel to one side of a triangle divides the other two proportionally, and conversely; the Pythagorean Theorem proved using triangle similarity. |

HSG.SRT.5 | Use congruence and similarity criteria for triangles to solve problems and to prove relationships in geometric figures. |

Understand Similarity In Terms Of Similarity Transformations | |

HSG.SRT.1 | Verify experimentally the properties of dilations given by a center and a scale factor: |

HSG.SRT.2 | Given two figures, use the definition of similarity in terms of similarity transformations to decide if they are similar; explain using similarity transformations the meaning of similarity for triangles as the equality of all corresponding pairs of angles and the proportionality of all corresponding pairs of sides. |

HSG.SRT.3 | Use the properties of similarity transformations to establish the AA criterion for two triangles to be similar. |

## Trigonometric Functions | |

HSF.TF: Extend The Domain Of Trigonometric Functions Using The Unit Circle | |

HSF.TF.1 | Understand radian measure of an angle as the length of the arc on the unit circle subtended by the angle. |

HSF.TF.2 | Explain how the unit circle in the coordinate plane enables the extension of trigonometric functions to all real numbers, interpreted as radian measures of angles traversed counterclockwise around the unit circle. |

HSF.TF.3 | (+) Use special triangles to determine geometrically the values of sine, cosine, tangent for π/3, π/4 and π/6, and use the unit circle to express the values of sine, cosine, and tangent for π–x, π+x, and 2π–x in terms of their values for x, where x is any real number. |

HSF.TF.4 | (+) Use the unit circle to explain symmetry (odd and even) and periodicity of trigonometric functions. |

Model Periodic Phenomena With Trigonometric Functions | |

HSF.TF.5 | Choose trigonometric functions to model periodic phenomena with specified amplitude, frequency, and midline.★ |

HSF.TF.6 | (+) Understand that restricting a trigonometric function to a domain on which it is always increasing or always decreasing allows its inverse to be constructed. |

HSF.TF.7 | (+) Use inverse functions to solve trigonometric equations that arise in modeling contexts; evaluate the solutions using technology, and interpret them in terms of the context.★ |

Prove And Apply Trigonometric Identities | |

HSF.TF.8 | Prove the Pythagorean identity sin2(θ) + cos2(θ) = 1 and use it to calculate trigonometric ratios. |

HSF.TF.9 | (+) Prove the addition and subtraction formulas for sine, cosine, and tangent and use them to solve problems. |

## Vector And Matrix Quantities | |

HSN.VM: Perform Operations On Matrices And Use Matrices In Applications. | |

HSN.VM.10 | (+) Understand that the zero and identity matrices play a role in matrix addition and multiplication similar to the role of 0 and 1 in the real numbers. The determinant of a square matrix is nonzero if and only if the matrix has a multiplicative inverse. |

HSN.VM.11 | (+) Multiply a vector (regarded as a matrix with one column) by a matrix of suitable dimensions to produce another vector. Work with matrices as transformations of vectors. |

HSN.VM.12 | (+) Work with 2 × 2 matrices as transformations of the plane, and interpret the absolute value of the determinant in terms of area. |

HSN.VM.6 | (+) Use matrices to represent and manipulate data, e.g., to represent payoffs or incidence relationships in a network. |

HSN.VM.7 | (+) Multiply matrices by scalars to produce new matrices, e.g., as when all of the payoffs in a game are doubled. |

HSN.VM.8 | (+) Add, subtract, and multiply matrices of appropriate dimensions. |

HSN.VM.9 | (+) Understand that, unlike multiplication of numbers, matrix multiplication for square matrices is not a commutative operation, but still satisfies the associative and distributive properties. |

Perform Operations On Vectors. | |

HSN.VM.4 | (+) Add and subtract vectors. |

HSN.VM.5 | (+) Multiply a vector by a scalar. |

Represent And Model With Vector Quantities. | |

HSN.VM.1 | (+) Recognize vector quantities as having both magnitude and direction. Represent vector quantities by directed line segments, and use appropriate symbols for vectors and their magnitudes (e.g., v, |v|, ||v||, v). |

HSN.VM.2 | (+) Find the components of a vector by subtracting the coordinates of an initial point from the coordinates of a terminal point. |

There is no teacher dashboard. Anyone can build or use activities. Kids and teachers do not have the option to track progress over time.