Students are introduced to the periodic table and the concept of atomic elements. The group discusses how all material in the Universe is composed of elements and that the atom is the smallest particle that still has the physical and chemical properties of any given element. As an exercise in statistics, the students participate in a counting experiment in which they sample a 'Universe bead mix' (where each bead color represents a different element present in the Universe) to estimate the overall composition of the Universe. They compare their findings of the Universe's overall composition with the composition of various different objects in the Universe that are represented by mixtures of rice, beans and other dried goods in jars. Finally, students are introduced to the idea that hydrogen fusion creates heavier elements inside a star.
a group of 20-25 students (grade range 5th-7th)
In this activity, each element is represented by a different color of bead. Mix the ingredients ahead of the planned activity in a large bowl. Using the same, or larger, size "measuring cup" for preparation as the students will each have during the activity. Mix the following:
In this activity, each element is represented by a different food. Prepare mixtures of these items according to the recipes below for the sources we are modeling. Note that these abundances are by volume, not weight. Because these items are approximately the same size, using dry measurements (volume) is very roughly equivalent to measuring numbers of atoms.
The number of bottle sets that you make is somewhat discretionary. The more sets you have, the smaller the group students can work in. 3-4 students working together is ideal. For a group of 25 students, that would be 6-8 bottle sets.
Place each mixture into a separate jar or bottle (these recipes are scaled for 8 oz. plastic bottles, available from many online suppliers). In each set, label each bottle with a number correlating to a specific source, and then record the key for later identification (ex. #1 = supernova). Cap all the jars/bottles. Taping shut the bottles when you are done can help to ensure that no food items escape into the classroom if this is a concern, as well as discourage students from opening the bottles, which may disrupt the activity and ruin the bottles for use at future events.
For each source, the recipes give the abundance (in %) and the volume of each element required in drymeasured cups (C), tablespoons (tbsp), and teaspoons (tsp). Note that the percentages may not add to 100% due to rounding amounts and excluding less significant elements.
|Carbonaceous Chondrite (a type of meteorite)|
|O||44.3%||5 tbsp + 2 tsp||Brown Rice|
|H||30.8%||4 tbsp||White Rice|
|Mg||6.2%||1 tbsp||Red Beans|
|Si||5.5%||1 tbsp||Pinto Beans|
|Fe||4.9%||2 tsp||Red Lentils|
|C||4.2%||2 tsp||Black Beans|
|O||42.2%||5 tbsp||Brown Rice|
|Fe||36.7%||4 tbsp + 3 tsp||Red Lentils|
|C||11.1%||1 tbsp + 1 tsp||Black Beans|
|Si||3.7%||2 tsp||Pinto Beans|
|Mg||2.8%||2 tsp||Red Beans|
|H||61.6%||1/2 C||White Rice|
|O||26.3%||3 tbsp + 1 tsp||Brown Rice|
|C||10.0%||1 tbsp||Black Beans|
|N||1.5%||1 tsp||Brown Lentils|
|H||92.1%||1/2 C + 3 tbsp + 1 tsp||White Rice|
|He||7.8%||4 tsp||Green Split Peas|
|N||78.0%||1/2 C + 1 tbsp||Brown Lentils|
|O||21.0%||2 tbsp + 2 tsp||Brown Rice|
|Ar||1.0%||1/2 tsp||White Beans|
For this demonstration, we use the following color correlations as an example, but the colors can be changed. Regardless of the colors you use, it is easier to see the layers if adjacent colors contrast with each other.
Make the clay star in 5 color-coded layers.
You may make this model out of Sculpey instead of clay if you would like a more permanent version. If you pursue this course, you should cut this model in half before baking it. This step can wait until the demonstration if you are using clay, but we found that pre-cutting the ball as the layers were added can be helpful for the demonstration because clay can be very hard to cut through.
Make extra fusion demonstration small clay balls
Some portions of this preparation can be very time-intensive. It goes faster with friends, so have a party to make bottles and clay balls!