8th Grade STAAR Math Reference Sheet & Formula Chart
Official Texas TEA formulas for Pythagorean theorem, linear slope, curved 3D solids (cylinders, cones, spheres), and interest calculations for Grade 8 Mathematics.
Linear Equations & Pythagorean Theorem (TEKS 8.4C, 8.5I, 8.7C)
Fundamental algebraic and right-triangle equations provided on the Grade 8 reference sheet.
| Mathematical Concept | Formula | Definition & Application |
|---|---|---|
| Slope-Intercept Form | y = mx + b | m is the slope (rate of change) and b is the y-intercept (0, b). |
| Slope of a Line | m = (y₂ - y₁) / (x₂ - x₁) | Ratio of vertical rise to horizontal run between points (x₁, y₁) and (x₂, y₂). |
| Direct Variation | y = kx | Linear relationship through origin where k is constant of variation (k = y / x). |
| Pythagorean Theorem | a² + b² = c² | In any right triangle, the sum of squares of legs equals hypotenuse squared. |
Surface Area & Volume of 3D Solids (TEKS 8.7A, 8.7B)
Formulas for prisms, cylinders, cones, and spheres (where P = perimeter of base, B = area of base, r = radius, h = height).
| Measurement | Solid Shape | Formula | Application & Notes |
|---|---|---|---|
| Lateral Surface Area | Prism | S = Ph | Perimeter of base P times prism height h. |
| Cylinder | S = 2πrh | Circumference (2πr) times cylinder height h. | |
| Total Surface Area | Prism | S = Ph + 2B | Lateral area plus both top and bottom bases. |
| Cylinder | S = 2πrh + 2πr² | Curved surface plus two circular bases. | |
| Volume | Prism | V = Bh | Base area B times height h. |
| Cylinder | V = πr²h (or V = Bh) | Area of circular base (πr²) times height h. | |
| Cone | V = ⅓πr²h (or V = ⅓Bh) | One-third the volume of a matching cylinder. | |
| Sphere | V = &frac43;πr³ | Four-thirds pi times the radius cubed (r × r × r). |
Personal Financial Literacy Formulas (TEKS 8.12D)
Formulas for simple and compound interest calculations on loan principal and savings.
| Financial Concept | Formula | Variables & Calculation Strategy |
|---|---|---|
| Simple Interest | I = Prt | I is interest amount; P is principal; r is annual interest rate (decimal); t is time in years. Total balance = P + I. |
| Compound Interest | A = P(1 + r)ᵗ | A is total balance including interest; P is principal; r is interest rate (decimal); t is time in years. Interest earned = A - P. |
Test Your Skills with 8th Grade STAAR Math Practice
Solve authentic Texas TEKS Pythagorean theorem questions, cylinder/cone volume problems, and interest calculations with instant step-by-step rationales.
8th Grade STAAR Math Reference Sheet FAQs
Essential questions about using the Grade 8 formula sheet, Pythagorean theorem, and graphing calculators.
Does the 8th Grade STAAR Math reference sheet include the Pythagorean theorem?
Yes. Under TEKS 8.6C and 8.7C, the Pythagorean theorem (a² + b² = c²) is explicitly provided on the Grade 8 reference sheet to calculate unknown side lengths in right triangles and distances on coordinate planes.
Are graphing calculators permitted on the 8th Grade STAAR Math test?
Yes! State testing policy mandates that every 8th-grade student must have access to a handheld graphing calculator (such as TI-84 Plus or TI-Nspire) or the embedded Desmos graphing calculator during the entire 8th Grade STAAR Mathematics exam.
What is the difference between simple interest and compound interest formulas on the chart?
Simple interest is calculated as I = Prt (where I is the interest earned, P is principal, r is annual interest rate as a decimal, and t is time in years). Compound interest is calculated as A = P(1 + r)ᵗ (where A is the total account balance including principal and compounded earnings).
How do students calculate the volume of cones, cylinders, and spheres using the reference sheet?
The reference chart provides volume formulas for cylinders (V = πr²h or V = Bh), cones (V = 1/3 πr²h or V = 1/3 Bh), and spheres (V = 4/3 πr³). A cone holds exactly one-third the volume of a cylinder with identical radius and height.