Page 120 - Coral Reef Teachers Guide

Coral Reef Teacher’s Guide What and Where are the Coral Reefs?

PRESENTATION:
Calcium Carbonate 1. The basic element of the coral reef is the cor-

and Coral al skeleton which is made of calcium carbonate
extracted from seawater by the hard coral polyp to
form a limestone base.
2. Explain that a test for calcium carbonate is to pour
Objective: Students will understand that coral
skel- etons are the basic structure of the coral vinegar over an object and observe it. If the object
reef, and that these skeletons are made of cal- bubbles and/or makes a fizzing sound, it prob- ably
cium carbonate, extracted by the polyps of hard contains calcium carbonate. (Note: sodium bicar-
corals from seawater to form limestone. They bonate also bubbles with vinegar.)
will use a vinegar test to identify calcium car- 3. Place the first two materials listed in separate
bonate in objects in their classroom dishes. Have the students tell you which ones
environment. they think contain calcium carbonate and why.
Interdisciplinary Index: Science, Language Arts 4. Perform the test, and identify the calcium carbon-
ate object.
Vocabulary: limestone, skeleton, calcium carbonate
5. Have the students choose items from the room
Materials:
that they think might be made from calcium car-
• a limestone rock or shell bonate. If chalk is not chosen, the teacher should
• two rocks other than limestone add it.
• a piece of chalk 6. Place each of the selected items in a separate dish
and pour vinegar over each one.
• pencil or other common object
7. Observe which items cause the vinegar to bubble.
• vinegar
8. Discuss which items are made of calcium carbon-
• a dish for each specimen
ate and contain the same material as coral skel-
etons. Since chalk is made of calcium carbonate, it
will bubble.
FOLLOW ‐ UP/EXTENSION:

Have the students write a description of what they
observed. Helpful hint: If you cannot observe the
bubbles, have students hold the container with the
calcium carbonate object near their ears and they
can hear the fizzing sound of the bubbles.

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