Learning Targets
- Explain why engineering drawings use standardized line patterns.
- Identify visible edges and hidden features in a selected view.
- Use consistent solid and dashed line patterns in a drawing.
IED Unit 1 • Lesson 1.2
Line Conventions
Focus question: How do different types of lines help engineers communicate clearly?
Mission Briefing
Today’s Plan
Use this page with the lesson presentation and your engineering notebook.
Success Looks Like
The line pattern alone clearly distinguishes visible edges from hidden features.
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Opening Prompt
Why might a dashed line communicate something different from a solid line?
Think first, then be ready to share a short response that connects the question to engineering communication.
Reveal: why this matters
Engineering line patterns act like a visual code. A solid line can show an edge that is directly visible, while a dashed line can show an important feature hidden behind a surface.
Core Skill
What We Are Practicing
Line conventions are standardized visual signals used in technical drawings.
Solid object lines show edges that are directly visible from the selected view.
Dashed hidden lines show important features that are blocked by another surface.
Interactive Model
3D Line Convention Explorer
Rotate the part, move to standard views, and compare how visible and hidden edges communicate its shape.
Loading 3D model…
Drag to rotate • Scroll or pinch to zoom • Arrow keys also rotate
Calculating dimensions…
Reference Drawings
Front, Top, and Right Orthographic Views
Compare each 2D projection with the interactive model. Use the buttons to align the 3D model with the matching standard view.
Study prompt: Identify which edges remain visible in all three views and which features appear differently when the viewing direction changes.
Lesson Interactive
Classify Visible and Hidden Edges
For each example, decide whether the line should be a solid object line or a dashed hidden line. This activity intentionally does not use centerlines or construction lines, which are introduced later.
| Feature in the Selected View | Line Sample | Your Classification |
|---|---|---|
| Outside edge directly facing the viewer | ||
| Side of a slot blocked by the front surface | ||
| Top corner visible from the chosen direction | ||
| Back edge of an internal recess |
Ask one question for each edge: can the viewer see it directly from this direction?
Your Task
Compare Visible and Hidden Edges
Use the Lesson 1.2 model and reference views to study how the same part changes when viewed from different directions. Focus only on visible object lines and dashed hidden lines.
- Choose one standard view and compare it with the 3D model.
- Trace or redraw the view using solid lines for visible edges and dashed lines for hidden features.
- Create a two-item key labeling the object-line and hidden-line patterns.
Quality check: Every line should match a real edge or feature in the selected view, and the two patterns must be easy to distinguish.
What You Will Submit
Visible-and-Hidden-Line Study
Submit a focused comparison using only the line conventions introduced in this lesson.
Submission standard: Use only the solid and dashed line patterns practiced in this lesson, and keep each pattern consistent.
Resources
Lesson Resources
Lesson 1.2 PowerPoint
Use the lesson slides for guided practice, interactive checks, and the exit ticket.
Introduction to Engineering Design
Return to the IED course hub for units, resources, certifications, and current course information.