The lesson focused on the factors influencing fabric length calculation for garments, emphasizing two main factors: the length of the garment and the number of pattern pieces required. The instructor explained the impact of using different fabrics, like velvet, which require specific layout directions due to their one-way fabric design to ensure a proper garment fit. Practical examples were provided to illustrate how fabric type, such as cotton or polyester, affects garment design and assembly, highlighting the importance of directional consistency in pattern layout.