Opposition groups have warned  demonstrators that they are likely to meet a tough response from the security forces.
The Iranian ‘green’ movement have already taken advantage of a number of state-sponsored events such as “Quds Day ” to organise demonstrations. According to media on Sunday most of Tehran's Internet links were down in what sources close to Iran's technical services said was “a decision by the authorities” rather than a breakdown.
Mojtaba Saminejad, blogger and human rights activist, writes [fa]:
As 7th of December [16th of Azar] approaches, arresting students and preventing them of studying becomes worse than ever. Again, the “military coup base” came to this conclusion that by massive arrests of students they can disturb the December 6th program and students’ gathering. But this year is different from other years, and students will have a great number of Iranian people there to support them. This day, the Student Day will became a National Day, but the coup agents will still ignore it.
Several citizens around the world have used YouTube to support Iranian protesters such as this woman from Germany who says that on December 7, ‘My heart is with you until you become free.’
Iranian citizens have launched Divarnevisi (meaning ‘writing on the wall’) a website where they publish posters, teach others how to write slogans in the street, and share the photos of the slogans and pamphlets from different cities of Iran.
We can find several examples of posters for December 7. Here is one example where we can see the photos of Iranians like Neda  who were killed after 12th of June election by the security forces.