Here is a 3 x 3 grid.
There are blue rectangles, red rectangles and where they overlap purple rectangles [blue+red=purple].
There is a pile of 9 pictures of animals.
Some pictures are mammals [put those in the blue rectangles], some pictures are animals which can swim [put those in the red rectangles] and some pictures are mammals and can swim [put those in the purple rectangles].
Drag 8 of the 9 pictures from the pile and drop them into the grid.
Do not bother about sorting at this stage as you can rearrange the position of the pictures at any time.
*Take care however, !!! when you drag in your last picture the grid becomes FROZEN.
To restart the activity just refresh the page.