There are three stages to this activity.
Part One practices the vocabulary in single form. Click on the start button once to make the images appear and then after a few seconds click again to make them vanish. Then have students raise their hands and say what there was. I usually have them say 'I see a ....' This can be in groups or individually. If you use the answer sheet you can click on the correct number to reveal their answer.
Part Two has 8 questions.
I generally have them make groups, then show the image and have one member of each group race to a teacher with their answer.
Part Three has two rounds and a demonstrate round.
I do the demonstration first. Click the start button once and let them see the image for a few seconds. Then click on the question button to reveal the question. Do one or two questions to get the idea.
When I do the real rounds I usually let them see the images twice. Once quickly and then a second time for a bit longer.