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Sample #1: Here is a modified version to include more items (PICTURES only)
I have purposely provide unequal number of items for each group to rule out the possibility of wild guess.
Matching Groups (Drag & Drop)
Drag the items from the light blue tray from the bottom and drop them to the grey area above so that they gather in the same group.
Once you have done so, a red button shall pop up to ask you to check your answer. Click on it.
If you have answered correctly, the items stay at where they are, otherwise the wrong ones shall automatically fall back to the tray below it.
Try again until you have all items matched the right grouping.