1. **Problem statement:** We have a large square composed of 16 smaller squares, each with an area of 4 square units. We need to find the side length of the large square. 2. **Understanding the problem:** The large square is made up of 16 smaller squares arranged in a 4 by 4 grid (since $\sqrt{16} = 4$). 3. **Formula for area of a square:** The area $A$ of a square is given by $A = s^2$, where $s$ is the side length. 4. **Find the side length of one small square:** Given the area of each small square is 4, we find its side length by solving $s^2 = 4$. $$s = \sqrt{4} = 2$$ So, each small square has side length 2 units. 5. **Find the side length of the large square:** Since the large square is 4 small squares wide, its side length is: $$\text{side length of large square} = 4 \times 2 = 8$$ 6. **Final answer:** The side length of the large square is **8 units**.