You have to play this game from inside. Click on the green flag, then click on the yellow button that says "New Item". An item will appear with a price. Click on the green buttons to get the coins you need, then drag them to the blue area to pay. When you drag the correct number of coins into the blue paying area, you get the item (in an imaginary way, of course). Click on the item you purchased to make a new item appear, or click on the green flag and yellow button again.
This activity is called "Uncommon Cents" because I couldn't find a way to make the Data variables for the price and money paid display only two decimal places. They kept displaying 3. I decided it would be better to keep it all in cents without using a decimal point to denote dollars. However, I always remind my students that this is not the usual way we use money and when they see 100 cents they should automatically think to themselves "one dollar". The math still works out the same though. :)