A set of silver web icons: an arrow pointing to the right, a success and a fail mark, and a question and an exclamation mark. Created in Inkscape 0.48 under Linux Mint Debian.
After going nuts looking for some icons to represent these group activities, I decided to make some. These are using a stylised petal shape but the principle can be adapted into another shape. One of the 'debate' versions initially looked like two people having a punch up being egged on by the crowd. Filled in shapes indicate full participation, hollow ones are passive, half-half are contributing to the activity.
The minimalist icons are designed to look great on any background and both black and white versions are ready for use. Included in the download are 96 png icons in sizes: 128x128, 64x64, 32x32 & 16x16. Fully editable illustrator file with all the icons is in the download.