Out of all of the toys I have reviewed these Magicubes from Geomag are the ones I recommend the most. They are magnetic building blocks and so clever and versatile. They teach children colours, counting and how to use their imagination. Building the blocks is great for their coordination.
You can use these blocks to teach your children so many different things. They are a great tool for teaching.
Geomag Magicube free building set of 24 Magnetic blocks has the basics of stem and the magnets help build shapes easily. There are available here. I cannot recommend them enough, and neither can my children.
