Graphical stories of motion

What the Activity is for

Students can walk-out target graphs, and so obtain a real understanding of what the story behind the graph is. The translation is between the graphical and the physical. The same technology also allows variations, as it's the act of translation that provides the key to understanding: you can phone a friend and have them reconstruct a graph just from a verbal description, walk out a graph just from the verbal description or walk out a graph from a set of vectors. Tune the translation to suit the class and what you want them to learn. In all cases the screen and display can provide a common reference point for the discussion. In this activity it's the graph that is the core representation.

What to Prepare

• a motion sensor and display
• a series of graphs to mimic, or other instructions

What Happens During this Activity

Here is one variation. Set up the motion sensor, directed at a space where there will be few stray reflections (important for those sensors that emit and detect pulses of radiation), and load up a target graph. Invite a student forward to walk-out the graph, using their torso as the target for the sensor and therefore the object whose motion is graphed.

Teacher: I'd like you to see if you can walk as this graph shows, to make another graph exactly like this one.

We'd expect you to need to use several prepared graphs, each with several students, to establish the pattern that you're focusing on through your choice of graph.

There are alternatives, some of which might be used as follow up.

Teacher: Here's a graph. Get your friend to redraw the graph, without showing it to them. Imagine you're phoning the friend.

Teacher: Here are a set of vectors, showing how the velocity changes. Walk out the graph of the motion shown by these vectors.