Parametric Heart Spreadsheet
Do you ever wish your spreadsheets were more romantic? Using parametric equations, you can construct a perfect heart shape, and this Excel file has everything you need to understand how the equations give the shape, as well as allowing you to edit the parameters and see how that changes the resulting plot. There's also a second sheet with the equations for a cardioid. The spreadsheet can be given to students directly, or kept as a cheat-sheet while they make their own. Great as part of a lesson on parametric equations, or just a fun activity to play around with.