This is an interactive pre-lab animation where the lab instructor creates a series of lab procedure steps and the student must put them in the order they are performed. The student would need to consult the lab procedure information in the lab guide to successfully order the steps. Typically, each student gets a "subset" of the procedure steps to order so that they don't have the exact same answer as a classmate . . . . for example, if there are 20 procedure steps, each student could get 15 of the 20 steps to "order."
In the example below, there are 17 procedure steps (listed) but the interactive display only lists 13 steps that must be ordered.
- Record your unknown number.
- Mass a clean, dry Pyrex test tube.
- Add 2.5 - 3.0 g Unknown to the test tube.
- Take the unknown to the Hood.
- Heat the unknown to decompose the ammonium bicarbonate.
- Determine the mass of ammonium bicarbonate in the mixture.
- Add ~ 5 mL water to the test tube.
- Heat the test tube with a Bunsen burner for ~ 60 seconds.
- Add a 2nd 5 mL of water to the test tube and heat gently for 60 seconds.
- Add a 3rd 5 mL of water to the test tube and heat gently for 60 seconds.
- Use a Bunsen burner to dry the wet sand.
- Determine the mass of sand in the mixture.
- Heat the salt water solution in the Evaporating Dish.
- Determine the mass of the salt in the unknown mixture.
- Discard the salt and sand in the trash container.
- Clean the used glassware with soap and water.
- Return the ironware to the appropriate location.
To order the steps, the student would . . .
- read the lab Procedure
- click and drag the steps to reflect the order they appear in the lab Procedure
- click the Submit button . . . . correct answers are displayed in green and incorrect answers in red
- click / drag the incorrect answers
- click the Submit button
- repeat until all steps are in the correct order
Some universities use this as a pre-lab assignment AND as an in-lab assignment - students log in to Chem21Labs at the beginning of lab and "order" the steps in a monitored environment to test their true knowledge of the procedure they are about to perform.
This ordering animation is also used as a homework problem type to order atoms and ions by atomic radii, electronegativity, ionization energy, electron affinity, etc.