THIS ROCK IS YOUR ROCK,
THIS ROCK IS MY ROCK
912 National Center
Reston, VA. 22092
Level: Grades 4 - 6
Estimated time Required: 30 - 40 minutes
Anticipated Learning Outcomes
- Students will develop good observational skills.
- Students will learn that rocks are made up of one or
Rocks are made up of one or more minerals. The individual minerals that
compose rocks have specific identifying properties such as hardness, crystal
shape, reaction with hydrochloric acid, and the color of the powdered mineral
when scratched on a streak plate. Some properties are more useful than others
to identify the mineral, depending on the mineral. The shape (not size,
though) of a mineral crystal is commonly helpful in identifying the mineral.
Colors of some minerals are useful for identifying the minerals, but in
other minerals color is very misleading. Many minerals can have different
colors. For example, the mineral quartz comes in white, pink, purple, and
The types and relative proportion of minerals that occur together in a rock
tell scientists the story of how that rock was formed. Rocks are named based
on how they formed, and by the types, amounts and sizes of minerals in the
rocks. One of the most important skills a geologist needs when studying
a rock is the ability to observe and describe what he or she sees.
- Enough different rocks or minerals similar in size and
shape for each student to have one. Rock and minerals samples can often
be acquired through geology departments, state geological surveys, and
local mineral and gem clubs.
- hand lenses
- pencil and paper
- Give each student or pair of students a rock or mineral
sample. Give the students 10 or 15 minutes to look at the samples, with
hand lenses, if available. Have students describe their sample, noting
the colors, weight, size, and/or shape. Before beginning, the teacher could
model the procedure by holding up one large sample, and writing on the
chalkboard observations about the sample.
- Samples are then collected and put into a pile at the
front of the room.
- Students exchange their original sample description with
another student or group for the detective phase. Using the rock or mineral
descriptions, the students will then try to find the sample. (5 minutes)
- The teacher then checks to see if each detective group
has the correct sample for their description sheet.
- Detective groups should then expand the original description
sheets with their own observations of the sample. (5 - 10 minutes)
- (Optional) Have the students repeat steps 2 - 4, and
see if the expanded descriptions and additional observations have made
this process easier.
- (Alternative) Instead of passing the samples around,
the teacher may want to hold up the samples and have students offer descriptive
terms that can be written on the blackboard. Students could then be handed
samples to identify based on the written descriptions on the blackboard.
- The students can discuss the advantages of having more
than one student add their observations to the rock descriptions.
- Students can create a booklet of the samples and their
descriptions for is play in the school library.