Running downhill in the Belgian forest
It may be winter, but this weekend is also allows the first opportunity of the year to get out into any National Park for free. If you are a parent, your children likely do not have school on Monday, and if you are a teacher, you likely don't work on Monday either. Why not enjoy nature?
So take a look at what parks are near you, bundle up, and get out there! If you are bringing children, make sure you take the time to just pick a spot and stay, and give them an opportunity to play anywhere and do what they please - you won't regret taking the time to step back and watch open-ended play at its best.