Rates: work problems · 3:27
Two Painters, One Room
Alice can paint a room in 6 hours. Bob can paint the same room in 3 hours. Working together, how long will it take them to paint the room?
Concept demo · prepared for Kaplan
Six SAT problems, explained the way a film would.
Each one is a three-to-four-minute narrated 3D film built around a single test question: the traps, the one picture that makes the idea obvious, the general rule. Every film has an interactive version where the numbers change and the set redraws itself.
Quadratics: the vertex · 3:27
The Fountain
A fountain shoots water from a nozzle 3 feet above a pool. The water's height in feet, t seconds after leaving the nozzle, is h(t) = −16t² + 32t + 3. What is the maximum height of the water?
Systems of linear equations: distance, rate and time · 4:26
Two Trains
A freight train leaves a station heading east at 40 miles per hour. Two hours later an express train leaves the same station on a parallel track heading east at 60 miles per hour. How many hours after the express leaves does it catch the freight train?
Average speed: total distance over total time · 4:05
The Round Trip
A cyclist rides from her house to the beach at 20 miles per hour and rides back along the same road at 30 miles per hour. What is her average speed for the whole round trip?
Circles: completing the square · 4:06
The Unfinished Square
In the xy-plane, the graph of x² + y² + 6x − 4y = 12 is a circle. What is the radius of the circle?
Similar triangles: proportions · 3:50
The Shadow
At a certain time of day, a flagpole casts a shadow 36 feet long. At the same time, a person 5 feet tall standing nearby casts a shadow 4 feet long. How tall is the flagpole?
Built as software, not video
Every frame is computed from the clock, so a film can be paused, scrubbed, re-timed to a new narrator, or re-rendered with different numbers. The same engine drives the film and the game.
A question, three traps, one picture
Each film follows the shape of a good tutor's explanation: state the question, show why the tempting answers fail, then let the set do the explaining with one camera move that is the argument itself.
What comes next
A tutor chat beside the widget, so a student can ask "what if Bob were slower?" and watch the set answer. Same engine, same films, a conversation on top.