Subjects

Case Study: Redesign a Checkout Flow

Model interview answer for the live design-interview prompt 'checkout has a 68% abandonment rate at the payment step — walk me through your approach' in 20 minutes: the clarifying questions that separate a strong candidate from a guesser, framing the problem as a Double Diamond Define step, generating and prioritizing distinct hypotheses for payment-step-specific drop-off, sketching a redesign tied to named interaction and visual design principles, and choosing a validation method sized to the time available.

User Research Methods

Covers the NN/g qualitative/quantitative × attitudinal/behavioral 2x2 for placing research methods, generative vs evaluative research mapped onto the Double Diamond, the core method toolkit (interviews, contextual inquiry, diary studies, surveys, card sorting/tree testing, analytics, A/B testing) with what each answers and its failure mode, a decision framework for choosing the right method under real constraints, sample-size reasoning for qualitative usability testing vs statistical significance, the classic research biases interviewers probe for, and synthesizing raw notes into actionable insight via affinity mapping.

Usability Testing and Evaluation

Covers moderated vs. unmoderated usability testing and the factors that decide between them, heuristic evaluation against Nielsen's 10 heuristics as a complement to (not replacement for) real user testing, the completion-rate/time-on-task/error-rate triad and why you need all three together, the System Usability Scale's exact 10-item structure and 0-100 scoring formula with Bangor/Kortum/Miller benchmarks, the think-aloud protocol and its common facilitation pitfalls, when A/B testing is the right tool versus when usability testing is, and the recruiting/sample-size/confirmation biases that undermine a study's findings.

UX vs UI and the Design Process

Covers what the UX/UI split really means beyond 'research vs visuals', the Double Diamond and Design Thinking process models and how they differ, ISO 9241-210 human-centered design, Lean/Agile UX vs waterfall handoff, how design job titles blur in practice, and the classic interview trap of reciting a process instead of adapting it to real constraints.

Interaction Design Principles

Covers Nielsen's 10 usability heuristics with concrete UI examples, the Gestalt principles of perceptual grouping (proximity, similarity, common region, closure, continuity), Fitts's Law and target sizing, Hick's Law and choice overload, Don Norman's affordance/signifier distinction and the flat-design failure mode, feedback loops and the 'dead click' problem, and the error-prevention-over-error-recovery hierarchy.

Design Metrics and Product Thinking

Covers Google's HEART framework and its Goals-Signals-Metrics companion process, the business metric vocabulary designers need (conversion funnels, activation, retention/churn), North Star metrics and how they should shape design prioritization, reasoning about design quality vs. shipping velocity as a cost-of-being-wrong tradeoff, techniques for quantifying UX impact to win stakeholder buy-in, and the risk of over-optimizing for a metric that's a poor proxy for the real goal — including where that risk shades into manipulative, dark-pattern territory.

Accessibility and Inclusive Design

Covers the WCAG POUR principles (Perceivable, Operable, Understandable, Robust) with a concrete example of each, the A/AA/AAA conformance levels and why AA is the real-world target, exact WCAG 2.1 AA contrast ratios (4.5:1 normal text, 3:1 large text and UI components), keyboard navigation and visible focus indicators, how screen readers build the accessibility tree from semantic HTML and ARIA, ARIA landmarks and labels, the Microsoft Inclusive Design framework's permanent/temporary/situational model, and a worked 'make this dropdown accessible' interview walkthrough.

Wireframing and Prototyping

Covers the low/mid/high fidelity spectrum and what question each level is built to answer, why higher fidelity is a tradeoff rather than a quality ladder, the cost-of-change curve that justifies validating structure before polish, fidelity vs. interactivity as two separate axes, how to choose a fidelity/interactivity combination for a given situation, the prototyping tools landscape framed for interview judgment rather than tool trivia, the risk of designing directly in code or a high-fidelity tool, and how to run the classic whiteboard sketching exercise.

Visual Design Fundamentals

Covers modular type scales and why a constrained set of sizes beats arbitrary pixel values, line-height and line-length rules grounded in how eyes actually track text, color as a functional (not just decorative) property with an explicit link to WCAG contrast and color-blind failure modes, the 8-point spacing grid versus layout-grid columns/gutters as two distinct systems people conflate, the four levers of visual hierarchy with a worked form redesign, Jakob's Law and where consistency is non-negotiable versus where novelty is safe, and the diagnostic question for knowing when a visual fix is the right fix versus a coat of paint on a structural problem.

UX Writing and Microcopy

Covers the distinction between voice and tone with a worked example, the what/why/how-to-fix structure for error messages, the difference between first-use and cleared/filtered empty states, progressive disclosure and tooltip overload in onboarding copy, why specific button labels prevent destructive mistakes, why lorem ipsum breaks real layouts and what content-first design does instead, and the localization pitfalls (text expansion, idioms, fixed-width containers) that microcopy written only for English misses.

Information Architecture and Navigation

Covers what information architecture actually is versus the navigation UI that surfaces it, the three organization schemes (hierarchy, sequence, matrix) and when each fits, the depth-vs-breadth tradeoff and Hick's Law, open and closed card sorting, tree testing as the validation step, Indi Young's mental-model-vs-system-model gap, the core navigation patterns (hub-and-spoke, tab bars, hamburger menus, breadcrumbs, mega menus) and how to choose between them, and when search should replace browse instead of papering over a broken structure.

Design Critique, Feedback, and Portfolio Presentation

Covers the 'I like / I wish / What if' critique framework and why it beats unstructured reactions, separating critique of the work from the person, the difference between vague and actionable feedback with concrete rewrites, how to receive feedback without getting defensive, the Problem/Process/Decisions/Outcome structure for presenting a case study in an interview, the most common portfolio mistakes that read as junior, and how to answer 'what would you do differently' well.

Case Study: Design a Mobile App From Scratch

The capstone of the UI/UX Design Interview track: a complete model answer to 'design a mobile app that helps people find and book last-minute fitness classes near them' worked exactly as a candidate would in a 30-40 minute whiteboard interview — clarifying questions, JTBD over persona framing, an explicitly scoped MVP, bottom-tab information architecture, wireframe-level screens with Fitts's/Hick's Law reasoning, empty-state and booking microcopy, map-accessibility considerations, HEART success metrics, and a closing risk statement — synthesizing personas/JTBD, IA and navigation, wireframing, interaction design, UX writing, accessibility, responsive design, and metrics from earlier in the track.

Responsive and Mobile Design

Covers the precise difference between responsive, adaptive, and mobile-first approaches and why mobile-first is now the default; breakpoints and fluid grids using relative units; the exact touch-target minimums (44x44pt iOS, 48x48dp Material) and their Fitts's Law justification; the key iOS HIG vs. Material Design differences and when to follow platform convention vs. diverge for brand consistency; mobile gesture vocabulary and the discoverability problem; and progressive disclosure as Hick's Law applied to small screens.

Personas, Journey Maps, and Jobs-to-be-Done

Covers proto-personas vs. research-based personas and the 'persona theater' trap, the Says/Thinks/Does/Feels empathy map, journey map structure with a worked e-commerce example, Jobs-to-be-Done and the Christensen/Moesta milkshake study with its functional/emotional/social dimensions, service blueprints and the frontstage/backstage/support-process distinction, and a decision framework for picking the right synthesis tool.

Design Ethics and Dark Patterns

Covers Harry Brignull's dark pattern taxonomy (confirmshaming, roach motel, forced continuity, sneak into basket, trick questions, misdirection, privacy zuckering) with a named example per pattern, the practical test for where persuasive design becomes manipulative, privacy-by-design and informed consent by default, GDPR and emerging dark-pattern regulation as a business risk beyond ethics, and a concrete escalation playbook for the classic interview scenario of being asked to implement a pattern that crosses the line.

Design Systems, Components, and Dev Handoff

Covers the real distinction between a style guide, a component library, and a full design system; Brad Frost's atomic design methodology (atoms through pages) worked through a product card example; design tokens as platform-agnostic data that make theming and rebrands a single-source edit; component library governance (single source of truth, versioning, the rule-of-three contribution model); how Figma Dev Mode and shared tokens change what a 'redline' communicates and what still needs a handoff conversation; when a formal design system pays off versus becomes premature overhead for a small team; and component API design as a design decision, not just an engineering one.