Treasure Boats
Teacher Instructions
Through this experiment the concepts of physical reactions, density, and buoyancy are explored.
Physical reactions are changes that occur to the physical nature of a substance.
Density is the measure of mass contained in a given unit of volume. If mass is the measure of how much ‘stuff’ there is in an object, density is a measure of how tightly that ‘stuff’ is packed together.
Buoyancy (flotation) is the upward force on an object created from the surrounding liquid. The more contact the object has with the liquid the more force is pushed upon it; therefore, it is more likely to float.
Experiment 1: Creating the Treasure
Objective: To clean pennies with salt and vinegar
Instructions
1) Cover tables with large plastic trash bags
2) Fill clear tubs with water (at least 6 inches deep works best) and place between two-three students to share.
3) Each student is given a small bowl/container, a spoon, and approximately 15 pennies
4) Mix about 200-milliliters (mL) vinegar and a spoonful of salt in bowl (for the younger students, teachers may want to pre-mix the solution in a larger container and then pour into the individual bowls.)
5) Stir slowly to dissolve all salt
6) Have each student dip one penny half way into the liquid and hold for 20 seconds.
7) Remove penny and observe what happened
8) Place the remaining pennies in the solution and watch the reaction
9) Once shiny, remove the pennies with the spoon and put into the tub of water to rinse.
Further experiments: Use other types of coins as well
Total time: 15 mins
Experiment 2: Building the Boat
Objective: To create an object out of the material given that will float and hold the most pennies. Students will gain basic principles of boat design while having first-hand experience with concepts of buoyancy and density.
Demo: To show the concept of buoyancy, demonstrate with a piece of aluminum foil. Place a flat sheet on the surface of the water while having the students observe. Take the same sheet and crumple it into a ball. Once again, place it in the water and watch it sink. Discuss the differences in the shapes and what happened. This demonstration will have the kids begin thinking about what makes a good boat design.
*Note: You may want to discuss strategies for building the boat. Do they have to start over if there is a tear in the side? Also, mentioning that they do not have to use the whole time given to work on their boat. If they are happy with it, they can be done before time is up.
Instructions
1) Group children into pairs, each pair can share a water tub
2) Each student will be given the same amount of material (either clay, aluminum foil, or Styrofoam)
3) Their task is to build a boat that will hold the most treasure.
4) Give them about 15-20 minutes to test their boat in the water on their own. For younger students, it takes about 15 minutes to find a good design that floats.
5) Make a name card out of construction paper and place boat on it.
6) Have an official classroom wide competition to see whose boat will hold the most treasure.
Total time: 40 mins
Group Discussion:
a) What are the features of the winning boat?
b) What happened during testing that was helpful?
c) How did your boat change?
d) Discuss how it relates to the scientific method. They each reflected a hypothesis of what they thought would help the material float. They produced data from testing (sink or float, number of pennies), and the data lead to new hypotheses (which leads to more testing).
Materials (per 20 students)
About 300 dull pennies
20 table spoons salt
4 liters white vinegar
20 small plastic bowls
20 plastic spoons
10 large tubs about 6 inches deep (about half filled with water)
2 packages (of five large sticks) non-hardening modeling clay (each student
gets half chunk)
10 sheets of aluminum foil
paper towels
large trash bags to cover table
References:
www.pbskids.org/zoom/activities/sci.boatsaloat.html
www.juniorengineering.usu.edu
Treasure Boats Worksheet (Grades 3-8)
Name: ______Date: ______
Experiment 1:
Treasure has been found! Your first job is to clean the coins to make the treasure shiny once again.
1) Mix vinegar and one spoonful of salt in your bowl.
2) Hold one coin half way into the solution for 20 seconds.
3) Remove coin.
Describe what happened.
______
______
______
4) Place the remaining coins in the solution and watch for changes.
5) Once the coins are clean, remove them with the spoon.
6) Put clean coins in water tub to rinse.
Experiment 2:
Your second job is to build a boat out of the material given to you to hold the shiny coins. How many treasure coins can your boat hold? Make a guess (prediction) of how many pennies it will hold before you put the boat in the water. Record your guess and what you actually counted.
Boat Data Guess/Prediction How many coins did it hold?
Test 1Test 2
Test 3
Test 4
Test 5