This is the initial worksheet I created. If you click on it, you'll get a full 8.5x11 in. version you can print out.
After you introduce the penny as equaling one cent, you have the children color the pennies.
Next, have them write 1 cent on each coin, using the cent symbol.
Finally, explain to them that 5 pennies equal 5 cents, which is the same thing as a nickel. Have them draw circles around each group of 5. There are 40 pennies on this sheet, so they'll end up with 8 groups. (If you have gifted children who need the challenge, let them use a different color marker to group them in sets of 10 to equal dimes.)
Don't forget to bring in several versions of the coin so they can see that the penny differs slightly, and isn't one set picture. Or, better yet, tell everyone that for their homework assignment, the day before you plan to introduce this concept, they each need to bring a penny.