This is one of the 41 activities your child can play in Busy Little Brains.
You can use the mouse to drag the blocks wherever you like, building with the different shapes or writing with letter and number blocks. You can also write with the blocks by typing letters and numbers on the keyboard. When clicked on or typed, each block says its shape and, if appropriate, its letter or number, reinforcing those concepts.
The Fall Down button makes your block creation fall to the bottom of the screen.
There are 13 different backgrounds. For a new background, either click on the background or click on the small, changing triangular picture near the upper right corner.