...or ride it...or simply follow it.
My brother has recently become addicted to Line Rider. This is a simple thing, in which you essentially make a line (or many lines), then send a teeny little man riding along on a sled, on the line you've just created. The challenge comes in making the line interesting, and keeping the man sliding without falling. There's also a bunch of movies to watch of some amazing lines that others have made.
Along a similar line (pun intended), I recently found a book that I will be adding to my collection of children's books. It's called, "Follow the Line," by author/illustrator Laura Ljungkvist, and is simply a joy to look at. One continuous line leads you through the entire book, creating city buildings, waves and sailboats, forest animals, and some fabulous faces. The text of the book is very basic, asking counting questions about what you see, which is perfect, because this line has so much to see. I'm looking forward to ordering this book and another called "Follow the Line Through the House."
Now, keep in line...