The Base Kit is the starting point for teaching kids how to play with electronics. It comprises 10 modules, enough to show the basics of how electronics work and to even build simple projects, all without plugging in a soldering iron. You can teach your kids how to build an alarm, a lamp, a portable fan, and even a light sensor in moments, with all of the components clearly labeled to show how different electronics parts work together. It's a bit sparse for serious tinkering, but all models work with each other, and you can easily expand your collection piecemeal or with additional kits from LittleBits.
This isn't a very complex set, but it's an good starting point for getting kids into engineering. If you really want a lot of different parts to work with, though, you should consider jumping straight to the Editors' Choice Gizmos & Gadgets Kit, or the network-capable Smart Home Kit.
Each LittleBit module in the Base Kit measures about an inch wide and is color-coded by the connectors on each end (except for power modules, which have only one LittleBit connector and a jack for a power source, like a battery pack or a USB adapter). Blue modules are power sources, pink modules are control devices like buttons and sensors, green modules are output devices like lights and motors, and orange modules are wires and splitters for placing and arranging different modules away from each other. Everything you build needs one blue power module, and at least one each of the pink input and green output modules.
The magnetic connectors on each module make hooking them up very easy. The magnets work with small plastic tabs on each connector to properly align modules in the right direction. You can't have a module upside-down or backwards in your project, because it simply won't stick. Small marks on the corners of the connectors and user-friendly text on the white board of each module further help you keep track. With the colors, magnets, and labels, it's almost impossible to jumble up your modules.