SATs, or Standard Assessment Tests, are standardised tests administered in schools in the United Kingdom to assess students' academic progress and attainment at various key stages of their education. These tests are part of the National Curriculum assessment program and are typically taken by students at the end of key stages, including Key Stage 1 (KS1) for Year 2 students (aged 6-7), and Key Stage 2 (KS2) for Year 6 students (aged 10-11).

The primary purpose of SATs is to measure students' attainment in core subjects such as English (including reading, writing, and SPaG - spelling, punctuation, and grammar) and mathematics. SATs provide a standardised way of assessing students' knowledge, skills, and understanding against predetermined criteria set out in the National Curriculum.

SATs results are used to measure individual student progress, as well as to evaluate the effectiveness of schools and education systems at local, regional, and national levels. SATs are also used to inform the determination of target grades in secondary school. Target grades are intended to provide students, teachers, and parents with an indication of the level of academic achievement that students are expected to attain by the end of a particular stage or qualification. SATs results from Key Stage 2 are often used as a baseline assessment to help predict students' potential performance in secondary school. Secondary schools may use students' SATs scores, along with other factors such as teacher assessments and baseline tests, to set individual target grades for each student in key subjects such as English and mathematics.

The timing for when your child should start preparing for SATs can vary depending on individual factors such as their age, academic ability, and learning style. In the UK, students take Key Stage 2 SATs in Year 6.

While some children may benefit from early exposure to SATs-style questions and practice, others may prefer to focus on building foundational skills before tackling exam preparation. Start preparing for SATs gradually by incorporating practice activities and exercises into your child's regular study routine. This could include working on practice papers, reviewing key concepts, and developing effective study strategies tailored to their learning style. However, be mindful not to place undue pressure on your child to start preparing for SATs too early or to focus solely on exam preparation at the expense of broader learning experiences.

It is also important to consult with your child's teachers, school, or educational advisors for guidance on SATs preparation strategies and resources. They can provide valuable insights and recommendations tailored to your child's specific needs and circumstances.

Ultimately, the decision of when to start preparing for SATs should be based on your child's individual readiness and academic goals. By taking a proactive and supportive approach to SATs preparation, you can help your child feel confident and prepared to excel in their exams when the time comes.

In the United Kingdom, the subjects tested in SATs include:

1. English:
- Reading comprehension: Assessing students' ability to understand and interpret texts, including fiction, non-fiction, poetry, and plays.
- Writing: Assessing students' ability to write effectively for different purposes and audiences, demonstrating grammatical accuracy, clarity, and coherence.
- Spelling, Punctuation, and Grammar (SPaG): Assessing students' knowledge and application of spelling rules, punctuation usage, and grammatical concepts.

2. Mathematics:
- Number and Place Value: Assessing students' understanding of number concepts, including place value, rounding, and negative numbers.
- Calculations: Assessing students' ability to perform addition, subtraction, multiplication, and division using mental and written methods.
- Fractions, Decimals, and Percentages: Assessing students' understanding and application of fractions, decimals, and percentages in different contexts.
- Measurement: Assessing students' knowledge of units of measurement, conversions, and calculations involving length, mass, capacity, time, and money.
- Geometry: Assessing students' understanding of properties of 2D and 3D shapes, angles, symmetry, and position.
- Statistics: Assessing students' ability to collect, organise, and interpret data using tables, charts, and graphs.

These subjects and topics are assessed through a combination of standardised tests, which typically include a variety of question formats such as multiple-choice questions, short-answer questions, and longer-form questions.