Final answer:
The underlined parts in exercises 2–5 are depicted in dot drawing and area model sketches to simplify and visually illustrate mathematical concepts, such as objects represented by dots, shaded areas corresponding to other areas, vector addition, and the construction of geometric shapes.
Step-by-step explanation:
To understand how the underlined parts in exercises 2–5 are represented in the dot drawing, area model sketch, we need to consider them in the context provided. For example, in one of the exercises, it was mentioned that object A was isolated and represented by a dot in the diagram. This means that in a dot drawing, objects of interest can be simplified to dots for clarity. Similarly, an area model sketch might refer to illustrations where areas are demarcated, like the shaded blue area which corresponds to the red area or the equal sections on the color wheel game. Such models provide a visual representation that simplifies complex concepts like vector addition, as shown in the directions for combining arrows to represent vectors.
When sketching, it's important to first isolate the object or area of interest and then proceed to represent it visually. For instance, in one of the problems, the significance of circling the object in gray is emphasized, as it helps focus the attention of the learner on the forces acting on that specific object. This teaches the student to sketch selectively and purposefully.
Another approach taught is how to draw an ellipse around two fixed points using pins and a string, which is a practical way to render that geometric shape. Details like the area under the curve illustrate how the visual representation contributes to the understanding of concepts. Therefore, each underlined part in the exercises correlates to a specific element within these sketches and models, reinforcing graphical interpretation and problem-solving skills within the math curriculum.