Educators and K-12

Tools in this group

• Readability Scores (Flesch-Kincaid) - Flesch-Kincaid Grade Level and Flesch Reading Ease for any text. Word / sentence / syllable counts. Public-domain federal formula.
• Statistics Quick-Read - Mean, median, mode, range, variance, and standard deviation (sample and population) for a list of numbers.
• Quadratic Formula and Discriminant - Real or complex roots, discriminant sign, and vertex of the parabola for ax^2 + bx + c = 0.
• Scientific Notation and Significant Figures - Convert any number to m * 10^n form; count significant figures from the input string.
• Significant Figures (count + round) - Count sig figs in a number; round to a target N. Leading zeros not significant; trailing zeros after a decimal ARE.
• Genetic Codon Table (DNA / RNA) - Translate an in-frame DNA or RNA sequence to amino acids using the standard genetic code.
• Number Base Converter (2-36) - Convert between any two integer bases from 2 to 36. Shows decimal / binary / octal / hex side-by-side.
• GPA Calculator (Weighted + Unweighted) - Standard US 4.0 / 5.0 GPA. One course per line: letter, credits, optional honors / AP track. Bonus +0.5 honors / +1.0 AP on passing grades.
• Confidence Interval (Proportion or Mean) - Wald z-interval for a sample proportion or a sample mean. Flags small-n cases where Wilson / Clopper-Pearson or a t-interval is more appropriate.
• Sample Size for a Target Margin of Error - The inverse of the proportion confidence interval: the sample size n needed so a Wald margin of error meets a target. n = z^2 * p(1-p) / E^2, rounded up. A survey wanting +/- 3 points at 95% with the worst-case p = 0.5 needs 1,068 responses. A planning figure; use Wilson / Clopper-Pearson for small p or n.
• System of Two Linear Equations - Solve a1*x + b1*y = c1; a2*x + b2*y = c2 via Cramer's rule. Reports unique / infinite / no-solution; shows the determinant.
• Lexile Band by Grade (CCSS Stretch) - Grade-to-Lexile target ranges (K to 12) summarized from publicly published state-DOE bulletins implementing the CCSS Appendix A stretch alignment. Teacher governs text selection; Lexile is a MetaMetrics trademark.
• Standards-Based Grade (Mastery 1-4) - Weighted overall mastery from per-standard levels (1-4) and optional major / supporting / additional priority. Letter equivalent per AAS / NWEA conversion; school registrar governs the transcript grade.
• Bell Curve / z-Score and Percentile - z = (x - mu) / sigma; percentile from the standard normal CDF (Abramowitz + Stegun 26.2.17); curve letter band per the 68-95-99.7 rule. Teacher governs whether a normative curve is appropriate.
• Alternate Readability Formulas (SMOG / Coleman-Liau / Gunning Fog / ARI) - Four additional reading-grade formulas beyond Flesch-Kincaid: SMOG (McLaughlin 1969), Coleman-Liau (1975), Gunning Fog (1952), and ARI (Smith + Senter 1967). Same text input as Y.1.
• Periodic Element Reference (Electronegativity / Configuration / Oxidation) - Per-element lookup of period / group / block / Pauling electronegativity / electron configuration / common oxidation states. Covers H through Kr plus Ag / I / Au / Hg / Pb. By atomic number, symbol, or name.
• Pearson Correlation (r, R^2, significance) - Pearson r and R^2 for paired x / y series, with the t-test (t = r sqrt(n-2) / sqrt(1-r^2), n-2 df) and the two-tailed p-value from the Student-t CDF. Per OpenIntro Statistics Ch. 8.
• Chi-Square Goodness-of-Fit - Chi-square = sum((observed - expected)^2 / expected) on k-1 df, the p-value from the chi-square CDF, and a reject / fail-to-reject verdict at alpha. Expected entered as counts or proportions; flags expected counts below 5. Per OpenIntro Statistics Ch. 6.
• Linear Regression (slope, intercept, R^2) - Least-squares fitted line (slope, intercept), R^2, residual standard error, the slope t-test with a two-tailed p-value, and an optional prediction at a given x, for paired x / y series. Per OpenIntro Statistics Ch. 8.
• Grade-Curve Scaler - Flat-add, square-root, or linear rescale-to-target-mean grade curve, clamped to [0, 100]. Estimate only; the instructor's gradebook governs.
• Final-Exam Grade Needed - The score needed on the final to reach a target course grade, plus the maximum and minimum possible final grades, by weighted average.
• Weighted Category Grade - Overall course percent and letter grade from a list of categories (percent and weight), normalized by the sum of weights for a partially-complete term.
• Two-Sample t-Test - Welch's two-sample t-statistic, Welch-Satterthwaite df, p-value, significance flag, and mean difference, reusing the bundled Student-t CDF.