Sketching Tools Basics

Overview

Students learn to create simple 2D sketches in OnShape using three fundamentals: lines, circles, and rectangles. They will apply measurement/constraints by constructing a triangle-like workflow conceptually (different cases: one solution, multiple solutions, or none) while practicing standard triangle/shape reasoning from geometry as applied to design.

Learning intentions

Students will be able to:

• draw accurate basic sketches (lines, circles, rectangles) in OnShape on a selected plane
• add dimensions to sketches to control size (and understand how constraints affect outcomes)
• reproduce a sketch at a different scale using given measurements (scale reasoning)
• explain whether a set of angle/side requirements would determine a unique shape, multiple shapes, or no shape (using a simple sketch example)

Success criteria

• I can start a sketch on the correct plane and create a line, circle, and rectangle.
• I can add and edit dimensions so my sketch matches a target specification.
• I can rescale my drawing to a new scale factor and keep the proportions correct.
• I can justify when information would lead to a unique triangle, multiple triangles, or no triangle (informally, with sketches).

Curriculum links

• Geometry — Draw geometric shapes with given conditions and notice when conditions determine a unique triangle, more than one triangle, or no triangle.
• Geometry — Solve problems involving scale drawings by computing actual lengths/areas and reproducing drawings at a different scale.
• Geometry — (Supporting connection) Use slicing/plane section ideas to understand sketches as 2D representations of 3D objects.

Lesson structure (45 minutes)

1. 0–5 min · Hook (Quick Demo + Question). Teacher demonstrates in OnShape how changing a dimension changes the sketch and asks: “If two side lengths are fixed and the included angle changes, what might happen to the shape—one, multiple, or none?” Students do a quick think-pair-share and record one prediction in their notebook.

2. 5–12 min · Direct teach (OnShape sketch essentials). Teacher models: selecting a plane, starting a sketch, drawing with Line, Circle, and Rectangle tools, and using dimension tool to lock size. Students follow along on their device, creating an empty sketch and placing one line segment, one circle, and one rectangle.

3. 12–20 min · Guided practice (Make it match). Teacher shows a target set of dimensions (for a small “design plate” containing a rectangle, circle centered on a point, and two connecting line segments). Students recreate the target sketch, checking accuracy by comparing measured/entered values, and adjust until it matches.

4. 20–28 min · Scale reasoning station (Scale the sketch). Teacher provides a “rescale card” (example: original width 80 mm → new width 120 mm, so scale factor is 1.5) and reviews how to scale corresponding lengths. Students rescale their own drawing in OnShape (using either re-entered dimensions or a scaled reference approach) and confirm at least three corresponding lengths.

5. 28–36 min · Constraints case mini-task (Unique / multiple / none). Teacher introduces a sketch scenario: “We want a triangle where side lengths are (a) 5 and 7 with angle 60° vs (b) sides 5 and 12 with angle 60° vs (c) angles 30°, 45°, and one missing angle.” Students classify each as likely unique, multiple, or none by sketching small cases on paper (no need for exact math) and then connect the idea to “what happens when constraints are insufficient or inconsistent.”

6. 36–43 min · Create & submit (One complete design). Teacher posts the final requirement: Students submit a single sketch containing: one rectangle with given dimensions, one centered circle, and two lines that meet at a point (with dimensions added). Students finalize the sketch and take a screenshot or save/export as directed by the class workflow.

7. 43–45 min · Exit ticket (2 questions, fast). Teacher collects an exit ticket:

• Question 1: “Scale factor from 60 mm to 90 mm is ____; a 25 mm feature becomes ____ mm.”
• Question 2: “Given three angle measures vs. two sides and an included angle, does it tend to determine a unique triangle, multiple triangles, or none? (Choose one.)” Students answer independently.

Resources

• Student devices with OnShape access
• OnShape templates or starter document for each student (with pre-set units)
• Dimension specification cards for the guided practice target
• Rescale cards with scale factor prompts
• Pencil, notebook paper for quick sketch classification
• Projector/teacher demo screen
• Screenshot/export instructions sheet (printed or displayed)
• Timing slide to keep pace (Hook → Practice → Scale → Constraints → Submit)

Assessment

• Formative during guided practice: teacher checks that students can place tools and add dimensions that match targets
• Formative during scale station: quick check that at least three corresponding lengths scale correctly
• Formative during constraints mini-task: teacher listens for “unique/multiple/none” language with a brief justification
• Exit ticket: scale calculation accuracy and classification choice tied to constraint sufficiency

Differentiation

• Support: Provide a “dimension checklist” (Select plane → Start sketch → Draw → Add dimensions → Lock/confirm) and sentence starters for exit ticket justification (e.g., “This would be multiple because…”).
• Support: Offer a smaller first target sketch for students who need fewer features, then require only the rectangle + circle, with lines added if time allows.
• Extension: Students can add one extra constraint (e.g., a tangent relation if available in OnShape) or rescale to two different scale factors and compare proportionality.
• EAL/SEN: Use visual examples with labeled dimensions, keep instructions short, and allow the constraints classification to be done with simple yes/no checks before choosing the final category.