English Vocabulary · Grade 9 Live Review Preview

9th Grade Vocabulary Words

Ninth grade marks the transition to high-school reading and writing across literature, argument, research, biology, physical and Earth science, algebra, computing, world history, civics, and geography. This level develops precise academic and domain-specific vocabulary while strengthening context, nuance, source evaluation, figurative language, and evidence-based communication.

This independently authored 800-word beta curriculum is arranged in twenty-three pages of up to thirty-five words. Pages containing words 1–500 include five cloze questions drawn only from that enhanced range; words 501–800 remain fully visible and editable as list pages while the expanded practice layer is developed. Each row includes a subject-field label and an editable word-study note about a transparent affix, compound structure, capitalization, or dictionary base form. The cited Grade 9 resources calibrate difficulty and study skills only; all learner-facing definitions, examples, quizzes, and descriptions are original KSSR copy.

Please note: the vocabulary lists for grades 9~11 have been selected to ensure no overlap with the previous grade level. If the words are too specialized or difficult for you, please go back to grade levels 4~8 and review the words on those pages.

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Words 421–455 of 800
#	Word	Details	Meaning	Sample sentence
421	factorization	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Suffix focus: -ization forms a noun for a process of making or becoming.	因数分解	Factorization changes x squared minus nine into the product of x minus three and x plus three.
422	greatest common factor	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: greatest + common + factor. Study the complete expression as one field-specific unit.	最大公約数	Six is the greatest common factor of eighteen and twenty-four.
423	difference of squares	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: difference + of + squares. Study the complete expression as one field-specific unit.	二乗の差	The difference of squares x squared minus sixteen factors into two binomials.
424	perfect square trinomial	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: perfect + square + trinomial. Study the complete expression as one field-specific unit.	完全二乗三項式	The expression x squared plus six x plus nine is a perfect square trinomial.
425	radical expression	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: radical + expression. Study the complete expression as one field-specific unit.	過激な表現	The radical expression square root of fifty simplifies to five square root of two.
426	rational expression	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: rational + expression. Study the complete expression as one field-specific unit.	合理的な表現	The rational expression is undefined when its denominator equals zero.
427	absolute-value equation	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: absolute + value + equation. Study the complete expression as one field-specific unit.	絶対値方程式	The absolute-value equation has solutions two units on either side of five.
428	compound inequality	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: compound + inequality. Study the complete expression as one field-specific unit.	複合不等式	The compound inequality describes all values between negative one and four.
429	interval notation	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: interval + notation. Study the complete expression as one field-specific unit.	間隔表記	The solution x greater than three is written in interval notation with a parenthesis at three.
430	coordinate pair	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: coordinate + pair. Study the complete expression as one field-specific unit.	座標ペア	The coordinate pair negative two, five lies in the second quadrant.
431	direct proportion	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: direct + proportion. Study the complete expression as one field-specific unit.	正比例	Distance and time are in direct proportion when speed remains constant.
432	inverse proportion	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: inverse + proportion. Study the complete expression as one field-specific unit.	反比例	For a fixed trip, speed and travel time are in inverse proportion.
433	slope-intercept form	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: slope + intercept + form. Study the complete expression as one field-specific unit.	傾き切片形式	Slope-intercept form displays a line's slope and vertical intercept directly.
434	point-slope form	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: point + slope + form. Study the complete expression as one field-specific unit.	点と斜面の形	Point-slope form makes it easy to write the equation from a point and a slope.
435	standard form	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: standard + form. Study the complete expression as one field-specific unit.	標準形式	The equation was rewritten in standard form with integer coefficients.
436	system of inequalities	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: system + of + inequalities. Study the complete expression as one field-specific unit.	不平等系	The solution to the system of inequalities is the overlapping shaded region.
437	linear inequality	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: linear + inequality. Study the complete expression as one field-specific unit.	線形不等式	The linear inequality includes points above the dashed boundary.
438	exponential growth	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: exponential + growth. Study the complete expression as one field-specific unit.	指数関数的成長	Compound interest produces exponential growth.
439	exponential decay	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: exponential + decay. Study the complete expression as one field-specific unit.	指数関数的減衰	Radioactive material undergoes exponential decay.
440	percent change	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: percent + change. Study the complete expression as one field-specific unit.	変化率	The price rose from forty to fifty dollars, a percent change of twenty-five percent.
441	depreciation	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Suffix focus: -ation commonly forms a noun naming an action, process, or result.	減価償却	The car's depreciation was steepest during its first year.
442	conditional probability	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: conditional + probability. Study the complete expression as one field-specific unit.	条件付き確率	The conditional probability of rain changes when dark clouds are already present.
443	permutation	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Suffix focus: -ation commonly forms a noun naming an action, process, or result.	順列	Each different ordering of the three books is a permutation.
444	combination	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Suffix focus: -ation commonly forms a noun naming an action, process, or result.	1. 合併 2. 結合 3. 統合	Choosing three committee members from ten is a combination.
445	sample survey	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: sample + survey. Study the complete expression as one field-specific unit.	サンプル調査	The sample survey contacted randomly selected households.
446	observational study	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: observational + study. Study the complete expression as one field-specific unit.	観察研究	The observational study compares sleep habits and grades without changing either.
447	controlled experiment	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: controlled + experiment. Study the complete expression as one field-specific unit.	管理された実験	The controlled experiment assigns plants to different light levels.
448	population parameter	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: population + parameter. Study the complete expression as one field-specific unit.	母集団パラメータ	The true average height of all trees in the forest is a population parameter.
449	sample statistic	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: sample + statistic. Study the complete expression as one field-specific unit.	標本統計量	The sample mean is a sample statistic used to estimate the population average.
450	mean absolute deviation	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: mean + absolute + deviation. Study the complete expression as one field-specific unit.	平均絶対偏差	A small mean absolute deviation indicates that values cluster near the mean.
451	population variance	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: population + variance. Study the complete expression as one field-specific unit.	母集団の分散	Population variance increases when observations spread farther from the average.
452	z-score	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: z + score. Study the complete expression as one field-specific unit.	Zスコア	A z-score of two places the value two standard deviations above the mean.
453	normal distribution	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: normal + distribution. Study the complete expression as one field-specific unit.	正規分布	Adult measurement data often approximate a normal distribution.
454	skewness	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Suffix focus: -ness forms a noun naming a quality or state.	歪度	A few very high incomes create positive skewness.
455	correlation coefficient	noun Study Field: Grade 9 mathematics, computing, and data-literacy term Word study: Term structure: correlation + coefficient. Study the complete expression as one field-specific unit.	相関係数	A correlation coefficient near zero indicates little linear association.

Vocabulary reading and practice

Planning a Survey

Reading practice for pages 13–15. Five relevant words are highlighted.

English reading

A survey team plots each response as a coordinate pair and calculates a correlation coefficient to describe the linear association. A strong association does not prove direct proportion or causation. The team also uses conditional probability to compare subgroups, then considers every permutation of question order to test whether sequence changes responses.

Japanese translation

A reviewed translation is not available for this passage yet.

Reading comprehension

1. What does the correlation coefficient describe?

It describes the linear association between variables.

2. Does a strong association prove causation?

No, a strong association does not prove causation.

3. Why test each permutation of question order?

The team wants to see whether order changes responses.

Vocabulary quiz

Choose the dictionary equivalent for each of 5 selected words.

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Sources and curriculum references

These references guide selection and calibration. Definitions, sample sentences, readings, questions, and teaching notes are independently written and reviewed.

9th Grade Vocabulary Words

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