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The numbers are the worked example from the W5 slides (whole milk powder 0.5000 g, 0.1000 N HCl, blank 0.30 mL, titration 14.86 mL); the equipment is drawn schematically and the real appearance varies by brand.
Teaching notes & sources
Each act follows predict → observe → explain → compare → apply: s0 only records your prediction (no answer yet); s1–s4 ask their question after the animation, and a correct answer unlocks the next act; s5 has two questions in turn. The stage, captions and progress bar share one paused timeline, so nothing animates on its own; leaving the page or switching tabs pauses it.
Sources of the numbers (W5 slide calculation check): whole milk powder %N 4.079 → ×6.38 = 26.0%; melamine C₃H₆N₆ is 66.6% N, and every 1% mixed in adds 4.25 percentage points of apparent protein; bread flour with 6.25 instead of 5.7 is overestimated by 9.6%; theoretical %N of ammonium sulfate 21.20%, lysine hydrochloride 15.34%.
This version uses synchronized text captions and has no narration; the pre-lab video and this page share the same storyboard and drawing components.
W5 Protein (Kjeldahl method) lab slides · Ch18 Protein Analysis (Nielsen) slides · Storyboard and QA design reference (FW1201/code-animation-explainer)