Mars for Earthlings > Lesson Modules > In-Class Activity 1- JELL-O 1-2-3

JELL-O 1-2-3 Planet Differentiation

In-Class Activity 1_Birth of Planets

Julia Kahmann-Robinson PhD and Marjorie Chan PhD, University of Utah Department of Geology & Geophysics


Explain the differentiation of JELL-O 1-2-3 and use this as an analogy to the differentiation of the Earth and planets in our solar system.


Try your recipe for JELL-O 1-2-3 several days in advance to make sure your recipe works and/or you are making it correctly to create three layers. Have images ready (or use the Image File for this module).


To engage students, show them a short clip on birth of the solar system video (National Geographic):


To explore the concept of differentiation, try an activity involving jello.

In Class activity 1 – Jello

Jello 1-2-3 recipe:

Differentiation is the concept of how different constituents of a planetary body separate out as a consequence of their physical or chemical behavior. The planetary body develops into compositionally distinct layers. Are there any other examples of differentiation students can think of (e.g., salad dressing oil and water)?


To further explain how differentiation occurs in planets, have students examine other references, such as:

Modified reading/ discussion on Solar Nebular Theory (lecture note reference)

Planetary Differentiation and Planet Comparison Overview

Mars vs. Earth size research: Brandon, Alan 2011. Nature 473, 460–461 (26 May 2011) doi:10.1038/473460a


To distinguish planetary classifications, provide the following reading for further information on Pluto.

Pluto and Planetary Body Classification


The Pluto debate shows how science evolves as new information becomes available, a fundamental component of the of the Nature of Science.

Have a class debate about whether or not Pluto is a planet.

New Horizon Probe to Pluto NASA Video (see homepage for link:

After in-class debate, students will write up a short 1 page cited discussion paper on their opinion regarding the classification of Pluto (see link for paper guidelines). Make sure students include and discuss the current planetary classification scheme.

Students will develop an analogy, as a class, between JELL-O 1-2-3 and planetary differentiation.