Topic: Calcium
Grade Level: 3-4
PA State Standards:
3.2.4.A4: Recognizing that combining two or more substances may create a new substance with
different properties.
3.2.3.A4: Use basic reactions to demonstrate observable changes in properties of matter (cooking,
burning, etc.)
3.3.3.A2: Describe the physical properties of minerals and demonstrate how minerals can be
tested for the different physical properties.
3.3.4.A2: Identify basic properties and uses of Earth’s materials including rocks, soil, water, and
gases of the atmosphere.
Objectives:
 Students identify where in their daily life they can find calcium of various forms (food, in
nature, etc.).
 Students identify calcium as an element and explain what happens when mixed with
vinegar.
 Students explain why the body needs calcium.
Student Materials: (~30 students, teams of 4-6)
 6 glass jars
 6 eggs
 6 plastic cups filled with gravel
Teacher Materials:
 Guide sheets for exploration phase (attached “Calcium is Crazy!”)
 Transparencies for elaboration phase
 Listening guide for explanation/elaboration phase
 Items containing calcium for engage phase (cheese, chalk, limestone rock, glass, light
bulb, paint, egg shell, bone, pearls, tooth paste, microwavable container, lipstick, wool
sweater)
 Large pan of gravel
 1 gallon of vinegar
 Evaluation sheets to assess students’ comprehension of content
Engage Phase:
 Ask students what they think of when they hear “calcium”. Write responses on board.
 Have table set up with items containing calcium in the front of the classroom.
 Middle of table has a line that defines what does and does not contain calcium.
 List to students what is sitting on the table.
 Call on students to come up to table and move the items they believe contain calcium to
the other side of the line. Do this with six students. Each moves ONE item.
 Ask students what the items on the table have in common with the words that are written
on the board.
 Ask students why they picked certain items that they did. Or, with students who didn’t
get to go up, ask what they believed contained calcium and why.
 Write on board students’ ideas.
 Pass out “Calcium is Crazy!” guide sheet to students. Give them a moment to read the
directions and look at the pictures and chart.
Exploration Phase:
 Arrange students in groups of 4-5
 Hold up a regular raw egg, ask students what they think would happen if you dropped the
egg. Students should predict the egg would crack. Then, demonstrate that you know a
way to make it bounce.
 Allow students to take a turn bouncing the egg
 Give each group one empty jar with one egg inside
 Ask students to predict what will happen when vinegar is poured into the jar. Discuss.
 Teachers and volunteers will pour vinegar into jar and fasten jar. Instruct students to
record/draw observations.
 Bubbles should form on the egg and within 3-4 minutes the egg should float to the top of
the jar. Once it has risen, allow the students to gently touch the top of the egg to feel how
it has changed. (At this time you may pass around the egg so other students get a chance
to bounce it as well)
 While the students are waiting for the egg to rise, the teachers and volunteers will take a
plastic cup full of gravel to each group and pour vinegar over that as well.
 Ask students to record observations.
Explanation Phase:
 Ask students to describe what the egg felt like after it had floated to the top of the jar and
what they observed once vinegar was poured onto gravel. As a class discuss thoughts,
predictions, questions, ideas, concerns, etc.
 During the class discussion, volunteers will distribute “Calcium is Crazy!” listening guide
 Explain that calcium (egg shell) dissolves in the presence of an acid (vinegar) resulting in
carbon dioxide/gas (bubbles)
 Describe to students that when gravel (limestone) and vinegar (acid) are mixed together
the acid eats away at the limestone resulting in a chemical reaction
Elaboration Phase:
 Slide 1: Shows the periodic table to reinforce the concept that calcium is an element.
 Slide 2: Example of an eroded limestone gravestone relates the effects of acid rain and
limestone to everyday life. Explain that the background behind the center picture is an
even more magnified view of erosion.
 Slide 3: Picture of raw egg without shell provides a second look at the results of the
activity during the exploration stage. Explain that vinegar is often used when dying eggs
because, as we learned, it eats away at the eggs outer shell so that the color from the dye
can seep into the egg better. Show example of dyed egg without its shell so students are
able to make connection to “their world”
 Slide 4: Explain that calcium is very important for human bodies, and its most well
known function is to form strong bones and teeth.
 Slide 5: Explain how calcium balance is one of the body’s highest priorities. It’s so
important that your body will take it from your bones if there is a deficit anywhere else.
 Slide 6: Describe Rickets Disease to show just how important calcium is for our bones.
Explain when blood levels of calcium are low our bodies produce a hormone that causes
calcium to be released from out bones. People with Rickets are losing so much calcium
from their bones, yet not producing enough to replenish them and it leads to weak arms,
legs (pictured: bowlegs), pelvis, and spine, but may be treated with braces or calcium
supplements. Mention that Rickets may also cause dental problems such as cavities or
holes.
 Slide 7: Identify the various stages of life that people need calcium, why and how much.
Children need calcium because their bones are still forming. Pregnant women need
calcium for the development of the fetus and to replenish their own calcium levels since
the baby is using most of hers. Senior citizens need calcium because as you age the cells
that build bone become less active and may cause Osteoporosis, the process of bone loss.
It effects more than 25 million people in the US.
 Slide 8: Explain different foods have different amounts of calcium available to take.
Describe that our body absorbs 50% calcium of caulifour, broccoli, and brussel sprouts.
30% of dairy, 20% of almonds, pinto beans, and sweet potatoes, and >5% of spinach.
 Slide 9: Throw on a cape and state “Super. That’s how milk makes you feel. The calcium
helps bones grow strong, so that even if you’re not from Krypton you can still have bones
of steel.” (Superman reference)
References:
Bennett, Ann T., Kessler, James H. 1997. Best of Wonderscience: Elementary Science Activities
Volume I. Delman Publishers.
Tocci, Salvatore. 2004. Calcium.
Websites:
http://www.livestrong.com/article/412778-why-does-our-body-take-calcium-out-of-ourbones-when-we-do-not-have-enough-calcium/
http://www.livestrong.com/article/231593-why-do-we-need-calcium-how-do-we-get-it/
http://www.historyforkids.org/scienceforkids/chemistry/atoms/doing/calcium.htm
http://www.historyforkids.org/scienceforkids/chemistry/atoms/calcium.htm
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001384/