a few typos: possibiilities, two-dimenaional

Yeah, I make a lot of intentional typos to encourage the Observable folks to make a spell-checker. :) Thanks!

Some food for thought on a very noble effort. This is a golden age for STEM education. Consider numbering equations so they can be referenced in the discussion. Eg: https://observablehq.com/@mariodelgadosr/swarmalator The 'Example', start/stop animations are nice. Another visualization would be a 3D chart to actually visualize how the PDE solutions are affecting specific x,y,z coordinates as a function of time. See the following two notebooks using Plotly for examples: https://observablehq.com/@mariodelgadosr/halfbreadths-table-prototype https://observablehq.com/@mariodelgadosr/3d-scatter-of-u-s-lower-48-with-plotly Finally, students would appreciate 'playing' with the equations to see change and effect. Here are a few notebooks where 'models' are dynamically visualized as a result of user interactions with controls and/or charts: https://observablehq.com/@mariodelgadosr/swarmalator https://observablehq.com/@mariodelgadosr/balmer-series-spectral-lines-of-the-hydrogen-atom https://observablehq.com/@mariodelgadosr/input-radiaslider https://observablehq.com/@mariodelgadosr/data-visualization-of-randomly-assigned-values-to-objects

@Mario - Thanks for the comments! Considering your comment on "playing with the equations", you might be interested in these, as yet unpublished, notebooks: https://observablehq.com/d/be104d0209b8e011 https://observablehq.com/d/ee5f334ac049a573 https://observablehq.com/d/cb1fcd590cbbea0e https://observablehq.com/d/af582bb307db8090

For x3dom, you can disable the space bar and 'd' key and other key functionality for a more student friendly experience: let scene = div .append('x3d') .attr('disableKeys', 'true') .attr('width', scales.w.toString() + 'px') .attr('height', scales.h.toString() + 'px') .append('scene');

It appears that the disableKeys attribute can be only 'true' for 'false'. It'd be nice to be able to disable specific keys. I agree that some keys lead to rather surprising behavior, but I rather like having 'a' and 'r' handy.