A procedure should be easy to follow. It should have step-by-step directions for conducting the experiment. Often it includes a sketch of how to set-up the experiment. The directions may be numbered to be sure they are done in the correct order.
Here's an example using the ice cube experiment.
Put two identical bowls on the counter.
Take two ice cubes out of the freezer and place one in each bowl.
Break one of the ice cubes into smaller pieces that are no larger than 1/4 the size of the whole ice cube.
Time how long it takes for all the ice to melt.
A good way to check the procedure is to ask someone else to read it, and then have them explain how the experiment is to be done. Often you can identify which steps need more details.