U.S. grade levels are not exactly the same as in Spain because of differences in the education systems.

In the U.S., the education system includes:

• Kindergarten (ages 5-6)
• Elementary School (grades 1-5 or 1-6, ages 6-11 or 6-12)
• Middle School (grades 6-8 or 7-8, ages 11-14 or 12-14)
• High School (grades 9-12, ages 14-18)
• College (18+)

In Spain, the education system is structured this way:

• Educación Infantil (ages 3-6), refers to pre-primary education in Spain which is not compulsory
• Educación Primaria (ages 6-12), equivalent to elementary school, divided into six academic years
• Educación Secundaria Obligatoria (ESO, ages 12-16), similar to middle school and the first two years of high school, divided into four academic years
• Bachillerato (ages 16-18), similar to the last two years of high school in the U.S., focused on preparing students for university or vocational training
• "Primaria" refers to primary school, with each "grade" equivalent to a specific year (e.g., "2º Primaria" is 2nd Grade).
• "ESO" (Educación Secundaria Obligatoria) is secondary education, split into four grades (1º to 4º).
• "Bachillerato" is the stage before university, similar to high school.
• "Universidad" refers to university-level education

Elementary Education United States: Early childhood education begins with kindergarten, targeting children aged 5-6. This level focuses on basic literacy, numeracy, and social skills.

Spain: In Spain, "Educación Infantil" serves children from ages 3-6. While not compulsory, it plays a crucial role in early development, emphasizing play-based learning.

Primary Education

United States: Elementary school in the U.S. spans grades 1 - 5 or 6 (ages 6-11 or 6-12). It covers a broad curriculum, including basic subjects like math, science, English, and social studies.

Spain: "Educación Primaria" in Spain corresponds to ages 6-12, similar to U.S. elementary school. It comprises six academic years, where students are introduced to a range of subjects in a more integrated manner.

Secondary Education

United States: U.S. education splits secondary schooling into middle school (grades 6-8 or 7-8) and high school (grades 9-12). Middle school serves as a transition, introducing a more complex curriculum and personal development skills. High school focuses more on academic and career readiness.

Spain: In contrast, Spain has "Educación Secundaria Obligatoria" (ESO) for ages 12-16, which is akin to combining U.S. middle school and the first two years of high school. This is followed by "Bachillerato" for ages 16-18, resembling the U.S. high school's final two years, with a focus on preparing students for university or vocational training.

We use the following table at SpanishReadability.com to match grade levels and students' ages for our Spanish readability formulas.

U.S. Grade Level	Spain's Equivalent	Student Age
Pre-Kindergarten	Educación Infantil (3-5 años)	3-5 years
Kindergarten	Educación Infantil (5-6 años)	5-6 years
1st Grade	1º Primaria (Primero)	6-7 years
2nd Grade	2º Primaria (Segundo)	7-8 years
3rd Grade	3º Primaria (Tercero)	8-9 years
4th Grade	4º Primaria (Cuarto)	9-10 years
5th Grade	5º Primaria (Quinto)	10-11 years
6th Grade	6º Primaria (Sexto)	11-12 years
7th Grade	1º ESO	12-13 years
8th Grade	2º ESO	13-14 years
9th Grade (Freshman)	3º ESO	14-15 years
10th Grade (Sophomore)	4º ESO	15-16 years
11th Grade (Junior)	1º Bachillerato	16-17 years
12th Grade (Senior)	2º Bachillerato	17-18 years
College	Universidad (University)	18+ years

The notation "º" after a number is not a superscript zero, but rather an ordinal indicator. In many Romance languages, including Spanish, ordinal numbers (like first, second, third in English) are denoted with a superscripted "º" for masculine ordinals or "ª" for feminine ordinals.

For example:

• "1º" (read as "primero") means "first" in masculine form.
• "2º" (read as "segundo") means "second" in masculine form.
• "1ª" (read as "primera") means "first" in feminine form.

1º Primaria means "first grade of primary school," 2º Primaria means "second grade of primary school," and so on. The ordinal indicator "º" is a grammatical feature in Spanish to denote the order or position of something.

Our table is accurate for general purposes, including using them alongside Spanish and English readability formulas. However, the table is not precise. Keep in mind:

1. Educational Systems Vary: The U.S. and Spanish education systems have different structures and curricula. While the table provides a general equivalence, the exact match of educational content and student maturity level might not be precise.
2. Age Variability: The age ranges are typical but not absolute. Students might be younger or older than the age range for many reasons, such as early schooling, grade skipping, or repeating a grade.
3. Readability Formulas Context: When using readability formulas, remember they often focus on linguistic and syntactic elements (like sentence length and word difficulty) rather than specific curriculum or educational standards. Therefore, while the grade level equivalencies provide a useful context, the primary factors in readability are usually language-based.
4. Cultural and Linguistic Differences: Readability isn't solely determined by grade level; it also involves cultural and linguistic nuances. Texts deemed readable for a specific grade in the U.S. might not translate to the same level of readability in Spain, due to differences in language, culture, and education.
5. Use with Other Measures: Use this table to quickly assess who your readers are—or use it as part of a broader assessment of who can understand your text and why.