请你做出我上传题目的讲解视频。在视觉效果上我希望更适合中国小学三年级学生理解学习。并且希望可以通过视频让学生感觉到趣味从而提升兴趣。特别需要在解题过程中注意的是，图绘解题的过程，不要出现明显的绘画错误。另外，要注意内容呈现的清晰度与精准度。保证视频完整的正常输出完毕。---**Textual Information:**
**Question Stem:**
一张桌面是长方形的餐桌，
妈妈用“拃”测得它的长约
8拃，宽约5拃。这张餐桌面
的面积约是（ ）平方分米。
**Other Relevant Text:**
妈妈的1拃
长约2分米
**Chart/Diagram Description:**
**Type:** Diagram illustrating a measurement method (hand span).
**Main Elements:**
* A drawing of a human hand, viewed from the side, resting on a surface.
* A double-headed arrow indicates the distance from the tip of the thumb to the tip of the index finger when the hand is stretched. This distance represents one "拃".
* A text box pointing to the hand span illustration contains the text "妈妈的1拃 长约2分米" (Mom's 1 zha is approximately 2 decimeters long).