There's several major brands of construction toys, and you've probably heard of some of them, such as LEGO, Technic and K'nex.
LEGO is by far probably the most popular construction toy, and almost every child has a set of LEGO or has played with it before. What makes LEGO so popular is that it is incredibly easy to build with because it is based on bricks. There are no complex piece designs, and pretty much everything snaps together vertically, which makes it ideal for youngger children. The pieces are often very detailed and the sets have different themes, with everything from castles and jungle explorers to space vehicles. These themes are ideal for spurring a child's creativity.
In a way, Technic is a more advanced form of LEGO. While LEGO only consists of basic bricks to stack on top of each other, Technic introduces a more mechanically oriented element with rods that can snap into the sides of bricks to allow for rotating structures. Unlike K'nex, Technic was not designed with size in mind, but mechanical detailing. The sets often come with many different sizes of gears, angled pieces and various shapes that allow for mechanically accurate designs.
K'nex is the most distinct of these construction toys because it completely eschews the brick design that LEGO and Technic use. Instead of bricks, K'nex uses rods and connectors to allow builders to create different structures with. In addition, the type of plastic used by K'nex is also much softer than that of LEGO and Technic, and allows for bending structures. However, K'nex has also released a Micro-K'nex line with smaller versions of standard K'nex pieces, allowing for smaller models. K'nex is ideal for building very strong and large structures because the pieces are comparatively large and the connections between pieces are also stronger.
Source by Timothy Keyes