Beacon Lesson Plan Library

How Dense Are You?

Jeri Martin

Description

How did Archimedes find the gold crown? Students relate how density is a value that describes the material of which the object is made and is not influenced by the object's shape or size in any way.

Objectives

The student determines the relationship between mass and volume of an assortment of common substances.

Materials

-Triple beam balance (1 per group of 2-3 students)
-Beaker 1000 mL (1 per group of 2-3 students)
-Water (source: sink and/or 1 pitcher per group of 2-3 students)
-Metric ruler (1 per group of 2-3 students)
-Metal cubes (2 per group of 2-3 students)
-Metal slab (1 per group of 2-3 students)
-Rectangular jewelry gift box (1 per group of 2-3 students)
-Calculator (1 per group of 2-3 students)
-Miscellaneous items that you select (need to have 10 items that float and 10 items that sink in water): cork, pebble, aluminum foil, small piece of wood and plastic (0.5 inches X 2 inches or smaller), rubber stopper, steel sphere, etc. (1 set per group of 2-3 students)
-Paper
-Pencil

Preparations

1. Make copies of the K W L chart, Density and Lab Safety Rubrics and Overhead master (Word) listed in the associated file.
2. Obtain 10 – 15 rectangular jewelry gift boxes. I have found that if I go to a major department store and tell them/have a letter stating that I am a teacher and need the materials,they will donate them. If you cannot find a department store to donate, then have students bring in an empty rectangular jewelry gift box for the day of the activity.
3. Obtain metal cubes and slab. These can be ordered from most scientific companies. Cost is usually between $8 - $10 per kit. (The kit includes 2 cubes, 1 slab, and 1 metric ruler.) If you are unable to purchase this kit, then you can modify the lab by using wooden blocks and slabs. The wooden blocks and slabs can be found in the toy section of most discount chain stores. I have also found them at stores. The highest price is $1.00 for their items. The other modification that would need to be made would be eliminating the QUESTION from the lab activity.
4. If you don’t have a sink or sinks as a water source for students, then you will need pitchers for students to have their water source in. These pitchers can be donated from a local restaurant or purchased at a discount chain store.
5. Collection of packets of 20 items, ten that sink in water and ten that float in water.

Procedures

1. Before beginning this lesson, the teacher should review and/or have just completed a lesson on metric measurement and lab safety.

2. Give students a copy of the Density and Lab Safety Rubrics. (See associated file.)

3. Give students a copy of the K W L chart for density. (See associated file.)

4. Discuss with students the K (what do you know) and W (what do you want to know) from the chart.

5. The L (what did you learn) will be completed at the end of this activity.

6. (A.) To check knowledge/skills for determining volume of a regular shaped object (means you can physically measure the length/width/height of the object) and mass, give each group one of the rectangular jewelry boxes, a triple beam balance, and a metric ruler.
(B.) Have one member of the group get out a piece of paper. Make sure they list each member's name on the sheet of paper. This person will copy the DATA CHART (listed below and/or top of next page) from the overhead and/or whiteboard.
(C.) Using the overhead master for length/width/height, demonstrate and have students measure the length/width/height of their jewelry boxes.
(D.) Record on DATA CHART. Determine the volume of the box (length X width X height).
(E.) Using the triple beam balance, determine the mass of the jewelry gift box.
(F.) Record on the DATA CHART.
(G.) Now, have students determine the density of their jewelry gift boxes (density = mass/volume).
(H.) Have students record the density of the jewelry gift boxes from the other groups.
(I.) Have students discuss why there is or is not a difference in the densities of the different jewelry gift boxes used in this activity. This discussion should help find any errors that a group made in their measurements for density. (Example: If 9 out of 10 groups have a density between 1.5 – 1.8 and the 10th group has a density of 3.5, there is some need for discussion and review of procedures.)

DATA CHART:
Jewelry gift box Length (cm) Width (cm) Height (cm) Volume (cm3) Mass (g) Density (g/cm3)

GROUP'S DENSITY OF JEWELRY GIFT BOXES


7. Students should now do the density lab.
A. Materials: (per group of 2-3 students) 2 metal cubes, 1 metal slab, metric ruler, triple beam balance, calculator (optional)
B. PROCEDURE: (1.) Have one member of the group get out a piece of paper. This person will copy the DATA CHART (listed below) from the overhead and/or whiteboard. Make sure they list each member's name on the sheet of paper.
C. Pick up the two cubes. The one that feels lighter to you will be cube #1, and the heavier one will be cube #2. (1.) With the metric ruler, measure the length, width, and height of cube #1. (Note: If it is a true cube, then all sides will be equal.) (2.) Multiply these values (length X width X height) and record the volume of cube #1 on the DATA CHART. (3.) Using the triple beam balance, find the mass of cube #1 and record on the DATA CHART. (4.) Find the density of cube #1 and record on the DATA CHART. (Density = mass/volume.) (5.) Repeat steps 2-3 with cube #2 and the slab. (6.) Answer the QUESTION at the end. (7.) Then, complete the DATA ON DENSITY section.

D. DATA CHART:
OBJECT VOLUME MASS DENSITY
CUBE #1
CUBE #2
SLAB

E. QUESTION: If the slab's density equals one of the cube's density, what does that tell you about the material in the slab and that of the cube?
DATA ON DENSITY:
METAL MASS (g) VOLUME (cm3) DENSITY (g/cm3)
89.0 10.0
15.8 7.9
Silver 36.75
Densities of some metals: Aluminum = 2.7 g/cm3; Copper = 8.9 g/cm3; Gold = 19.3 g/cm3; Iron = 7.9 g/cm3
Formulas: Density = Mass/Volume
Volume = Mass/Density
Mass = Density X Volume
Each group will turn in the DATA CHART and teacher will assess for accuracy.

8. DOES IT SINK OR FLOAT? (A.) Give each group a 1000 mL beaker, source of water (sink and/or pitcher filled with water) and a packet of twenty items - ten float in water and ten that sink in water. (B.) Have one member of the group get out a piece of paper. Make sure they put each member's name on the paper. (C.) Members needs to have out their Density K W L chart. (D.) On the sheet of paper the group needs to list/make a prediction about which items they think will sink and those that will float. (E.) Have one member pour 750 – 800 mL of water in the 1000 mL beaker. (F.) Select one of the items and place it in the beaker of water and record the name on your K W L chart in the appropriate section (float/sink). (G.) Repeat this procedure with the other items. (H.) Each group needs to clean up their area. (I.) Students are to turn in their K W L charts after completing the L part.

Assessments

The Density and Lab Safety rubrics are marked for each student as students go through the activities. The K W L chart and DENSITY LAB will be collected. The entire DENSTIY LAB and L section of the K W L chart will be assessed. Students having difficulty will need additional feedback and practice.

Extensions

1. The activity with the jewelry gift box. You can extend this activity by having students graph (histogram) the variations/similarities of the densities of the boxes. Students will need graph paper.
2. You can have students find the volume of irregular shaped objects by the use of water. Need 100 mL graduated cylinder, water and marble. Fill the graduated cylinder with 50 mL of water. Carefully angle the graduated cylinder and allow the marble to roll to the bottom. (note: marble should not be dropped in – will crack the graduated cylinder). The difference in the level of the water (say it is now 53 mL) 53 – 50 = 3 mL. The volume of the marble is 3 cm3. Water: 1 gram = 1 mL = 1 cm3. Water is the only substance that this conversion works for because its density is 1 g/cm3.

Web Links

Web supplement for How Dense Are You?
Density and Buoyancy lessons

Web supplement for How Dense Are You?
Density lesson plans

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