Pre-Algebra: Foundations for Algebra I
This is the year math stops being "follow the steps for this kind of problem" and starts being "figure out what kind of problem this even is." Your child will learn to handle really big and really small numbers with exponents, meet numbers that never end or repeat (like square roots that don't come out clean), solve equations that can honestly have no answer or infinite answers, understand what a function actually is, prove shapes are the same or similar instead of just eyeballing it, use the Pythagorean theorem, work with slope and straight-line graphs, solve two equations at once, and read real scattered data for a trend. By June this feeds directly into Algebra I, which assumes all of it is already solid — not something to re-teach.
Unit 1: Exponents, Powers, and Scientific NotationThis unit builds exponent notation from scratch: what a power actually means, the three rules for combining powers with the same base, then the strange-but-necessary extension to zero and negative exponents, and finally scientific notation for very big and very small numbers. It ends with comparing unfamiliar real-world quantities by their order of magnitude.9 skills ▸close ▾
- Positive integer exponent notation (base, exponent, power)Evaluate numerical expressions with positive integer exponents using order of operations.
- Laws of exponents (product, quotient, power-of-a-power rules)Apply the product-of-powers, quotient-of-powers, and power-of-a-power rules to simplify expressions with a single common base.
- Conditions under which the product-of-powers and quotient-of-powers rules applyDistinguish expressions where an exponent rule applies (same base) from superficially similar expressions where it does not (different bases, or addition instead of multiplication).
- The zero and negative exponent extension of the integer exponent patternExplain why extending the pattern of decreasing exponents forces the definitions a^0 = 1 and a^-n = 1/a^n.
- Scientific notation as a decimal times a power of 10Convert numbers between standard form and scientific notation for very large and very small numbers.
- Arithmetic operations on numbers in scientific notationPerform addition, subtraction, multiplication, and division of numbers expressed in scientific notation, including cases requiring re-normalization of the leading digit.
- Order-of-magnitude comparison of quantities in scientific notationCompare the order of magnitude of two unfamiliar real-world quantities given in different units, without being told which quantities to compare or which operation applies.
- The logical necessity of the zero/negative exponent extension across all nonzero basesGeneralize the exponent rules to justify why a rule that holds for positive integer exponents must also hold for exponent zero and negative integers, using an argument that would apply to any base.
- Common exponent-rule errors embedded in a worked solutionCritique a flawed worked example that misapplies an exponent rule (e.g. adding exponents with different bases, or mishandling a negative exponent's sign) and identify precisely where the reasoning fails.
Unit 2: The Real Number SystemStudents learn that not every number can be written as a clean fraction or a decimal that ends or repeats — these are the irrational numbers, and square roots of most whole numbers are their main example. Kids learn to estimate these roots without a calculator, place them accurately on a number line, and justify why a number is or isn't rational.9 skills ▸close ▾
- Perfect squares up to 225 and their square rootsGiven a whole number, identify whether it is a perfect square, and if so, state its square root.
- Square root and cube root notation applied to perfect squares/cubesEvaluate square roots of perfect squares and cube roots of perfect cubes without a calculator.
- The irrationality of square roots of non-perfect squaresExplain why the square root of a non-perfect-square must be irrational, using the definition of rational number as a ratio of integers.
- The rational/irrational classification of numbers presented in varied formsClassify a given number as rational or irrational based on its decimal expansion or its form (fraction, perfect-square root, non-perfect-square root, known constant like pi).
- Tenths-level estimation of irrational square roots using bounding perfect squaresEstimate the value of a non-perfect-square root to the nearest tenth by reasoning between consecutive perfect squares.
- Justified placement of irrational numbers on a number linePlace an unfamiliar irrational number on a number line and justify the placement in writing using bounding rational numbers.
- Ordering of mixed rational and irrational numbersCompare and order a mixed set of rational and irrational numbers (fractions, decimals, roots, pi) from least to greatest.
- The rational/irrational status of a genuinely novel numeric claimGiven a real-world claim about an unfamiliar irrational number (e.g. a newly defined constant), determine whether it could be rational, and justify the determination without prior exposure to that specific number.
- The limits of a finite decimal display as evidence of rationalityGiven only a decimal expansion with no visible pattern (e.g. from a calculator display truncated at 10 digits), decide whether the number could still be rational and identify what additional information would be needed to know for certain.
Unit 3: Linear Equations in One VariableKids extend equation-solving to messier equations — variables on both sides, distributing and combining like terms — and confront the fact that solving an equation can honestly end in 'no solution' or 'every number works,' not just a single number. The core image is a balance scale: whatever you do to one side, you do to the other.10 skills ▸close ▾
- One- and two-step linear equations in one variableGiven a one- or two-step equation like 3x + 5 = 20, execute the correct sequence of inverse operations to find x.
- Distribution and combining like terms in multi-step equationsGiven an equation requiring distribution and combining like terms, apply both procedures in the correct order to isolate the variable.
- Equations with variables on both sidesGiven an equation with variables on both sides, transform it into an equivalent equation with the variable on one side.
- The no-solution case as a logical outcome of equation-solvingExplain why solving an equation to a false numerical statement (like 3 = 5) means the equation has no solution.
- The three solution-count cases (one, none, infinite) for linear equationsClassify an equation as having one solution, no solution, or infinitely many solutions by examining its structure before fully solving.
- The invariant structure underlying the no-solution case across different-looking equationsCompare two structurally different equations that both simplify to 'no solution' and identify what they share.
- Real-world contexts modeled by one-variable linear equationsTranslate a real-world scenario describing two changing costs or quantities into a linear equation and solve for the unknown.
- Solution-count reasoning applied to a novel geometric/measurement contextGiven an unfamiliar word problem about strips of tape with unknown overlap, determine whether the situation forces a unique length, no possible length, or any length, and justify the classification.
- Structural cues (coefficient and constant relationships) that determine solution countGiven a set of four equations with matched surface complexity, sort them by solution count using structural reasoning rather than full solving.
- Like terms in an algebraic expressionRecall the definition of like terms and identify them within a multi-term expression.
Unit 4: FunctionsThis is where 'a rule that takes an input and gives exactly one output' gets formal. Students learn to spot a function in a table, a graph, an equation, or a description, use the vertical line test, and — the hard part — recognize when a table and a graph are actually describing the exact same function.8 skills ▸close ▾
- The definition of function as one output per inputGiven a set of ordered pairs or a table, determine whether it represents a function by checking whether any input repeats with a different output.
- The vertical line test as a graphical criterion for the function definitionApply the vertical line test to determine whether a graph represents a function, including jagged, piecewise, and curved graphs.
- Equivalence of a function across table and graph representationsGiven the same function presented as a table and as a graph, determine whether they represent the same rule by comparing corresponding input-output pairs.
- Rate of change as a constant difference indicating a linear functionGiven a function's equation, generate a table of input-output pairs and identify whether the rate of change between consecutive rows is constant.
- Rate of change and initial value as representation-independent quantities usable for comparisonGiven two functions in two DIFFERENT representations (e.g. one as a table, one as a verbal description), determine which has the greater rate of change by extracting rate of change and initial value from each.
- Construction of a function rule from an unstructured verbal description, including a non-constant rate caseGiven a real-world situation described in words with a changing rate at a threshold (e.g. a billing plan), construct a piecewise function rule and justify whether it is linear over its full domain.
- The distinction between co-variation and a valid function ruleExplain, using a specific counterexample, why a graph that co-varies smoothly can still fail the function definition.
- Linear versus nonlinear classification using rate-of-change evidenceClassify a set of real-world scenario descriptions as representing linear or nonlinear functions based on whether their rate of change is constant.
Unit 5: Transformations, Congruence, Similarity, and the Pythagorean TheoremThis long unit replaces 'these shapes look the same' with an actual argument. Kids define congruent and similar precisely — congruent means one figure can be slid, flipped, or turned onto the other; similar adds resizing. They build up the Pythagorean theorem from an area diagram they construct themselves, then use it for distances, including between two points on a coordinate grid.12 skills ▸close ▾
- Translations described by coordinate rules, e.g. (x,y) -> (x+3, y-2)Given a figure on a coordinate grid and a translation rule, plot the image and state the coordinates of each vertex.
- Coordinate rules for reflections over axes and other linesState the coordinate rule for a reflection over the x-axis, the y-axis, or a given horizontal/vertical line, and apply it to a figure.
- The distinction between rigid motions and dilations with respect to distance and angle preservationExplain why distance between vertices is preserved under translations, reflections, and rotations but not under dilations, while angle measures are preserved under all four transformation types.
- Congruence as the existence of a rigid-motion sequence between two figuresGiven two figures on a grid, generate and describe a sequence of rigid motions that maps one onto the other, and use that sequence to justify that the figures are congruent.
- Similarity as a rigid-motion sequence plus one dilation, with scale factor unknown at the outsetGiven two similar figures where the scale factor is not stated, determine the dilation scale factor and center that maps one to the other, then complete the congruence sequence to confirm similarity.
- Angle pair relationships formed by a transversal crossing parallel linesUse informal angle arguments (vertical, corresponding, alternate interior) to find unknown angle measures when parallel lines are cut by a transversal.
- The triangle angle-sum theorem, justified via parallel-line angle relationshipsConstruct an informal argument, using a transversal through a triangle's vertex, that the interior angles of any triangle sum to 180 degrees.
- An informal proof of the Pythagorean theorem based on area conservationUsing an area-based diagram (e.g. rearrangement of four congruent right triangles inside a square), explain why a squared plus b squared equals c squared for any right triangle.
- Unknown side lengths of right triangles in applied problems (ladders, screens, ramps)Apply the Pythagorean theorem to find an unknown leg or hypotenuse length in a right triangle presented in a real-world context.
- The converse of the Pythagorean theorem as a test for a right angleDetermine whether a triangle with three given side lengths is a right triangle, using the converse of the Pythagorean theorem.
- Distance between two coordinate points via a constructed right triangleCompute the distance between two points on the coordinate plane by constructing a right triangle from the segment and applying the Pythagorean theorem.
- Selecting and combining transformation reasoning and the Pythagorean theorem in an unfamiliar applied contextGiven a real-world scenario with no diagram (e.g. two ships' positions given as coordinates, or a 3-D box diagonal), decide independently which combination of transformation and/or Pythagorean reasoning applies and solve it.
Unit 6: Linear Relationships: Slope, Proportionality, and SystemsSlope stops being 'rise over run' memorized as a ratio and becomes a proven fact: similar triangles cut from the same line always have proportional sides, which is why a straight line has one constant rate of change everywhere on it. From there, students graph lines using slope-intercept form, separate proportional relationships (which pass through the origin) from linear ones that don't, and take their first pass at systems of two equations — solving by graphing, then by substitution.13 skills ▸close ▾
- Similar-triangle justification for constant slope on a non-vertical lineGiven two triangles formed under a line by drawing legs parallel to the axes at two different points, explain why the triangles are similar and why this forces the rise-over-run ratio to be constant.
- The slope formula (y2-y1)/(x2-x1) applied to two coordinate pointsCalculate the slope of a line from two given points using the slope formula.
- Proportional relationships graphed as lines through the origin, with slope equal to unit rateGraph a proportional relationship from a table or equation and identify the slope as the unit rate.
- Unit rate comparison across mixed representations of proportional relationshipsCompare two proportional relationships given in different representations (table, graph, equation, verbal description) to determine which has the greater rate.
- Slope-intercept form as a graphing and interpreting toolDerive and use slope-intercept form y = mx + b to graph a line given its equation, and explain what m and b represent in a real context.
- The origin test distinguishing proportional from non-proportional linear relationshipsClassify a given linear relationship as proportional or non-proportional by testing whether it passes through the origin.
- The intersection point of two graphed lines as the system's solutionEstimate the solution to a system of two linear equations by graphing both lines and reading the intersection point.
- The meaning of an intersection point as a shared input-output pair in a modeled contextExplain what the intersection point of two lines means in terms of the two real-world quantities each line represents.
- The substitution method for solving a 2x2 linear systemSolve a system of two linear equations algebraically using substitution, showing all steps.
- Strategic variable selection prior to substitutionGiven a system where neither equation has an isolated variable, decide which variable to isolate and justify the choice before solving by substitution.
- The one/none/infinite solution cases for a linear system, linked to identity and contradiction equationsDetermine whether a system has one, no, or infinitely many solutions by comparing slopes and intercepts, and connect each case to Unit 3's one-variable equation outcomes.
- System-of-equations modeling of a scenario from an unpracticed domainGiven a real-world scenario with two unstated relationships, drawn from a domain not used in this unit's pricing- and motion-based worked examples (e.g. population growth, mixture/concentration problems, or tank fill/drain rates), generate and solve a system of equations that models it, choosing an appropriate method and justifying the choice.
- Structural reasoning about simultaneous intersection using slope and intercept comparisons rather than computationGiven three graphed lines with no context, determine which two intersect at a point that also lies on the third, and explain how you know without computing coordinates.
Unit 7: Systems of Linear Equations: Modeling and ApplicationThis unit takes the systems skills from Unit 6 and points them at real situations — two constraints on the same two quantities at once. Students write systems from word problems, choose between graphing and substitution and defend the choice, and interpret what a system's solution (or lack of one) actually means in context.10 skills ▸close ▾
- The solution of a system as a point satisfying both equations simultaneouslyGiven a system of two linear equations, identify whether an ordered pair satisfies both equations by substitution and checking.
- The intersection point of two graphed lines as the system's solutionGraph two linear equations on the same coordinate plane and identify the intersection point as the system's solution.
- The substitution method for solving systemsSolve a system of two linear equations using substitution when one equation is already solved for a variable.
- The relative efficiency of graphing versus substitution as solution methodsCompare the graphing and substitution methods for a given system and justify which is more efficient for that specific system.
- Translation of a two-constraint real-world context into a system of equationsWrite a system of two linear equations from a real-world context describing two constraints on the same two quantities.
- The real-world meaning of a system's solution pointInterpret the intersection point of a graphed system in terms of the original context, stating what quantity and value it represents.
- The relationship between slope/intercept comparison and the number of solutions of a systemClassify a system as having one solution, no solution, or infinitely many solutions by comparing slopes and y-intercepts without fully solving.
- The real-world meaning of no-solution and infinite-solution systemsExplain, using context, why a system with no solution represents two constraints that can never both be true, and why infinitely many solutions represents the same constraint stated two ways.
- The full modeling cycle from context to justified system solutionGiven an unfamiliar two-constraint scenario with non-integer or fractional intersection values, construct, solve, and justify a system, choosing a method and defending that choice.
- The no-solution condition extended to standard-form equationsGeneralize the condition for a system having no solution to systems written in standard form, without being shown that form during instruction.
Unit 8: Bivariate Data and Lines of FitReal data is messy — points scattered around, not sitting neatly on a line. This unit teaches kids to spot a trend anyway, draw and compare lines that follow that trend, write the line's equation, use it to predict, and know that a prediction from a trend is not a guarantee for any one point. It also extends the same thinking to categorical data in two-way tables.12 skills ▸close ▾
- Patterns of association in scatter plots (positive, negative, none)Given a scatter plot, classify the pattern as positive, negative, or no association.
- Linear vs. nonlinear association, clusters, and outliers in bivariate dataDescribe, in words naming both variables, whether a scatter plot shows a linear or nonlinear pattern and note clusters or outliers.
- Informal line of fit placementDraw a straight line that follows the trend of a scattered but linear-associated dataset.
- Criteria for judging quality of a line of fitCompare two candidate lines of fit on the same scatter plot and justify which follows the trend more closely, citing specific points.
- Slope-intercept equation of a fitted lineWrite the equation of a fitted line in slope-intercept form and identify the slope and y-intercept from a graph.
- Contextual meaning of slope and intercept in a bivariate data modelInterpret the slope and y-intercept of a fitted line as statements about the real-world variables, including units.
- Interpolation using a line of fit, and reasonableness of predictionGiven a new x-value within the data range, use a fitted line's equation to predict a y-value and judge whether the prediction is reasonable.
- Two-way tables and relative frequency for categorical bivariate dataConstruct a two-way table from categorical data and calculate relative frequencies by row and column.
- Association between categorical variables via relative frequency comparisonUse relative frequencies in a two-way table to argue whether an association exists between two categorical variables.
- Complete line-of-fit modeling process applied to a novel datasetGiven an unfamiliar real dataset with two numeric variables never used in instruction, construct a scatter plot, fit a line, and justify the fit using evidence from the data.
- Evaluation of another student's line-of-fit reasoning against data evidenceCritique a peer's completed line-of-fit analysis (plot, line, and interpretation) and identify a specific improvement, using no formula for a 'correct' answer.
- The distinction between a statistical trend and an exact linear ruleExplain why a line of fit predicts a trend rather than an exact value for any individual data point.
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