Hands-on Activity: Anchors Away

Contributed by: Adventure Engineering, Colorado School of Mines


In the continuing (hypothetical) storyline of the Lost in the Amazon unit, students discover the relationship between an object's mass and the amount of space it takes up (its volume). As they create small boats using clay, they learn about the concept of displacement and how an object can float if it displaces enough water, and the concept of density and its relationship to mass and volume.
This engineering curriculum meets Next Generation Science Standards (NGSS).

A sailboat sailing on the Hudson River.
A sailboat floats on water due to displacement
Copyright © https://en.wikipedia.org/wiki/Hudson_River_Sloop_Clearwater#/media/File:Sloop_Clearwater3_-_Photo_by_Anthony_Pepitone.jpg

Engineering Connection

This activity and its associated lesson provides an opportunity for student teams to complete the engineering design process employed by practicing engineers including constructing and testing their boat designs. See the related unit's Engineering Connection for further explanation.

Learning Objectives

After this activity, students should be able to:

  • Measure an object's mass and volume using the appropriate tool.
  • Estimate, calculate and compare volume and surface area of given objects.
  • Measure the properties of objects using tools such as rulers and balances.
  • Observe, describe, measure and record changes in properties.

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Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  • Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost. (Grades 3 - 5) Details... View more aligned curriculum... Do you agree with this alignment?
  • Understand the concept of a unit rate a/b associated with a ratio a:b with b ≠ 0, and use rate language in the context of a ratio relationship. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
  • Use tools to gather, view, analyze, and report results for scientific investigations about the relationships among mass, weight, volume, and density (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
  • Use information and communication technology tools to gather information from credible sources, analyze findings, and draw conclusions to create and justify an evidence-based scientific explanation (Grade 7) Details... View more aligned curriculum... Do you agree with this alignment?
  • There are different forms of energy, and those forms of energy can be changed from one form to another – but total energy is conserved (Grade 8) Details... View more aligned curriculum... Do you agree with this alignment?
Suggest an alignment not listed above

Materials List

Each group needs:

  • two-pan balance with gram weights
  • large bowl, ~2–3 inches deep
  • non-drying modeling clay, one 1-inch diameter ball per student
  • 5-10 paper towels sheets
  • water in a pourable cup
  • 1 slender glass cup or other clear container; best of the container is of uniform size if possible, that is, almost a perfect cylinder; also choose a container that can be marked on; refer to procedure steps 12-15
  • 1 sharpie pen or china marker
  • small handful of at least three of the following materials to use as boat loads: small metal nuts (1/4-inch works well), paperclips, fish weights (without lead), dry beans, marbles; for best results, use objects that are denser than water
  • Student Guide Worksheet


(Refer to the storyline in Lesson 6.) Remember that your goal is to cross a river. You have only a limited amount of supplies and you need to design something to get you across the river!


Gather materials and make copies of the Student Guide Worksheet.

In advance, weigh each of the items that students will be using to fill their boats and provide those weight amounts to the students.

Wait until students have created their boats and answered questions 1-6 on the second page of the student handout before handing out the load materials for students to place in their boats (paperclips, marbles, etc.); this helps to keep students from becoming distracted by the loose additional items.

For the ball to float it must be converted to a bowl shape. It may also float if made hollow, like a balloon. If students need help, suggest that they think about how boats are made. How can large metal ships float?

(optional) Make a transparency of the data table to use with an overhead projector or write it on the classroom board; fill in the Material and Item Mass columns with those that will be used.

Note that the size of the boat determines the amount that can be held, but the Mass of Items column values should be very close in value for all materials for a specific boat.

Make sure students notice that the even though the clay now floats, its mass is still the same.

For the next activity, students will need "boats" made of the clay, so they should keep their creations.



Worksheets: Have student groups use the Student Guide Worksheet as a guide to conduct the activity. Review their data and answers to gauge their engagement and depth of understanding.


© 2013 by Regents of the University of Colorado; original © 2005 Colorado School of Mines

Supporting Program

Adventure Engineering, Colorado School of Mines


Adventure Engineering was supported by National Science Foundation grant nos. DUE 9950660 and GK-12 0086457. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: July 18, 2017