In Year 4, students typically learn about fractions. Here are some key concepts and skills that students may cover:

1. Understanding fractions: Students learn that a fraction represents a part of a whole. They learn to identify and name fractions using numerators and denominators.

2. Equivalent fractions: Students learn that different fractions can represent the same amount. They learn to identify and create equivalent fractions by multiplying or dividing the numerator and denominator by the same number.

3. Comparing fractions: Students learn to compare fractions using different strategies such as finding a common denominator or using visual models.

4. Adding and subtracting fractions: Students learn to add and subtract fractions with the same denominator by adding or subtracting the numerators and keeping the denominator the same.

5. Mixed numbers and improper fractions: Students learn to convert between mixed numbers and improper fractions. They learn to simplify improper fractions and convert them to mixed numbers.

6. Multiplying fractions: Students learn to multiply fractions by multiplying the numerators and denominators.

7. Dividing fractions: Students learn to divide fractions by multiplying the first fraction by the reciprocal of the second fraction.

8. Problem-solving with fractions: Students apply their fraction skills to solve real-life problems, such as finding fractions of a quantity or solving fraction word problems.

These are just some of the topics that may be covered in Year 4. The specific curriculum may vary depending on the country or educational system.