An activity I might run with year 2 or 3 classes would be for students to create an image using a software package; they could use Keynote or PowerPoint to create the image using shapes and shape combining tools (grouping, combining, excluding) as well as resizing and rotating. Like the image below, created in Keynote. Students would then write down the instructions for recreating their image and give those instructions to a partner. Students would then try to recreate the image from the instructions without seeing the actual image. Once students have finished they should compare images and talk about how their instructions could have been improved to get a better result.
With younger students I would limit the number of shapes students could use, and I might give them a particular image I want them to create (for example I might say “Using exactly 6 shapes create a house”). This would stop them from going overboard and creating images that are too difficult to recreate.