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  • Water Crystallization & Hydrogen Bonding

    Water Crystallization & Hydrogen Bonding
    Purchase access to the 3D stereolithography (.STL) files and accompanying lesson plan for Water Crystallization & Hydrogen Bonding model!
    Model Price: $3.99
    Hits the standard: ESS2-5: Plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes.
    Lesson Brief: Among the many ways that water influences the surface of the earth are freeze-thaw cycles that contribute to weathering and soil formation, and the accumulation of snow and ice, and the way that ice forms to create a floating solid. Understanding the way that water molecules join to form a crystalline structure is a key to understanding how water can break bedrock and form complex geometric shapes. This lesson examines how the change from unordered water molecules into the regular crystal lattice structure of frozen water gives ice properties that lead to geological processes such as soil formation and have helped shape the biology of Earth.

    Background: Hydrogen bonding that occurs when water freezes causes strong forces to orient the water molecules into hexagonal rings. Multiple stacked rings can be visualized as hexagonal prisms with oxygen molecules at the vertices. When additional hexagonal prisms bond together, they form shapes that radiate outwards at 60° angles to adjacent projections. Some units bond to the upper and lower surfaces and thus form additional layers or very straight needle-like structures of ice. The forces bonding the molecules together are very strong and cause the unordered and densely packed molecules to spread apart slightly as they take on the hexagonal structure during freezing. This slight (approximately 8% less dense) decrease in how tightly packed together the water molecules are causes ice to float on water and causes the water to expand as it freezes. This expansion causes water filled cracks in rocks to increase in volume, splitting bedrock. This expansion causes containers full of water to split open when frozen. Mineral particles in soil are partially derived from the freeze-thaw action of water on the underlaying bedrock. The decreased density that allows ice to float allows ice to insulate standing fresh water such as lakes and has likely played an important role in the evolution of life on the surface of the earth.

    Activity: Print the water crystallization model. This can be used to highlight how water crystallizes into ice. The change from “jumbled” water molecules into a hexagonal prism-based solid form can be used to show why ice is less dense than water. The abundance of 60° angles in ice crystals and snowflakes can be highlighted with the steps modeled as well.

    Figure 1: Render of the 3-D printed water crystallization model.

    posted in Models
  • The Life Cycle of Insects with Metamorphosis

    The Life Cycle of Insects with Metamorphosis
    Purchase access to the 3D stereolithography (.STL) files and accompanying lesson plan for The Life Cycle of Insects with Metamorphosis model!
    Model Price: $2.99

    Hits the standard: 3-LS1-1
    3-LS1-1: From molecules to Organisms: Structures and Processes
    Figure 1: Render of the 3-D printed Butterfly Life Cycle model.

    Develop models to describe that organisms have unique and diverse life cycles but all have in common birth, growth, reproduction, and death.

    Lesson Brief: Different groups of animals have different life cycles. All animals are born, develop into the adult stage, reproduce, and eventually die. Within the insect group of animals there are two main types of life cycle. The more ancient types of insects have direct development, while the more modern insects have indirect development and go through metamorphosis. This lesson and the accompanying model cover the life cycle of insects that go through metamorphosis.
    The more modern groups of insects go through a major change in form and function, metamorphosis. These insects include beetles, flies, butterflies & moths, and others. Almost all insect life cycles begin by leaving the mother as eggs. In the insects with indirect development, a larva, a worm-like young insect, hatches from the egg. These larvae are adapted to do one thing well: eat so that they can grow. They have simple bodies without wings, and sometimes do not even have legs. Caterpillars have extra “prolegs” that are not real legs but help them to hold onto plants as they eat. They get bigger by shedding their shell or exoskeleton and making a new larger one. This can happen 3 to 5 times as they get larger. When they are done eating and growing, they go through a very different type of growth stage called a pupal stage. The pupal stage is when the larva turns into an adult. The adult stage is shorter than the larval growth stage. The adult stage is winged and has legs. Adults eat less than the larvae. The adults move much more than the larvae and reproduce by laying eggs, completing the life cycle.

    Activity: Print out enough 3-D models of the butterfly life cycle (Figure 1) for students to have individually or in groups. This model is based upon the monarch butterfly. Ask students to write out the role of each of the four life cycle stages (egg, larval stages, pupa, and adult) are adapted to different roles in the development of the insect. Students may paint the model if desired. If students do paint the model, prime it first with an acrylic spray or brush-on primer. If this lesson is done in groups, each student may be responsible for painting and/or explaining one of the stages.

    posted in Models
  • RE: Teaching Aid Wish List: October 2019

    1. Platonic Solids: Explorations in probability, vote for the Cube, Hexahedron, Octahedron, Dodecahedron, & Icosahedron as a set!

    2. Protein Macromolecule: If you need a protein macromolecule in your class, vote here; useful as a stand-alone model or alongside our DNA macromolecule, DNAgo!

    posted in Teaching Aid Wish List
  • RE: Teaching Aid Wish List: August 2019

    Butterfly Chrysalis for August 2019:
    Additional Butterfly Chrysalis for August 2019:
    Additional Butterfly Pupae for August 2019:

    posted in Teaching Aid Wish List
  • RE: Teaching Aid Wish List: March 2019

    @JeffHolland The Animal Cell is available for purchase at:

    Just click the green button to Purchase The Animal Cell!

    posted in Teaching Aid Wish List
  • The Animal Cell

    The Animal Cell
    Purchase access to the 3D stereolithography (.STL) files and accompanying lesson plan for The Animal Cell model!

    Model Price: $8.99
    Hits the standard: LS1.A : Structure and Function

    • Systems of specialized cells within organisms help them perform the
      essential functions of life (HS-LS1-1).
    • All cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins, which carry out most of the work of cells (HS-LS1-1, HS-LS3-1).
    • Multicellular organisms have a hierarchical structural organization, in which any one system is made up of numerous parts and is itself a component of the next level (HS-LS1-2).

    Lesson Brief: This model of an animal cell is useful in lessons addressing any of the above standards. Organelles can be removed and sequentially added to the model as each is discussed. For testing, a single organelle could be included and the name and function of the organelle requested.

    Background: The cell is the basic unit of life. Multicellular organisms are composed of many such cells that may be specialized into different roles within different tissues that form organs. The cell itself contains different organelles that have specific roles in the cell. The basic cellular unit then is a good example of the hierarchical structure of organisms. The roles of the major organelles are listed below.
    Centrioles: act as a center for the scaffolding involved in DNA separation during cellular fission. Golgi body: packages proteins and lipids for intra- and extra-cellular transport.
    Lysosome: vesicle containing enzymes for breaking down unnecessary biological molecules. Mitochondria: organelle that produces energy through respiration.
    Nucleus: organelle that contains the DNA in the form of chromosomes.
    Rough endoplasmic reticulum: Organelle that houses the ribosomes and is responsible for
    protein synthesis.
    Secretary vesicles: vesicles that transport unneeded materials out of the cell.
    Smooth endoplasmic reticulum: organelle responsible for making hormones and lipids.

    posted in Models
  • DNAgo: The Building Blocks of DNA

    DNAgo: The Building Blocks of DNA
    Purchase access to the 3D stereolithography (.STL) files and accompanying lesson plan for the DNAgo: The Building Blocks of DNA!

    Model Price: $7.49

    Hits the standard: HS-LS1-1. Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells.
    Lesson Brief: The DNAgo model is an intuitive model of how DNA is assembled from component molecules to encode genetic information. It serves several purposes. It shows how the 4 base pairs and the double helix scaffold are not molecularly complex by having the 5 different atoms involved labeled. The DNAgo model is more intuitive than a traditional ball-and-stick molecular model because the 6 individual molecules are shown as complete sub-units with the bonds between these represented. This allows students to form an intuitive mental model of how DNA encodes information.

    The model may be used to show students the 6 different sub-units in DNA. These can then be assembled into the helix scaffold before showing how the monomers bond to the scaffold and are paired with their matching monomers (i.e., arginine with thymine, cytosine with guanine).

    Background: The genetic information encoded within DNA is conveyed through the sequence of 4 monomers: arginine, cytosine, guanine, and thymine. These bases are held in sequence upon a double helix that is formed of alternating phosphate and deoxyribose sugar molecules. Spanning between the two helices that form the DNA scaffold, arginine pairs with thymine and cytosine pairs with guanine. This pairing allows the DNA to be replicated. The sequence of base pairs along a section of the DNA, called a gene, determines the nature of the protein that is created from that sequence.

    Activity: Print the DNAgo model. In the slicer software specify to print the molecules flat and the chemical bonds upright. Use adhesive to attach the bonds (Figure 1) to the molecules— cyanoacrylate glue works well if the ends are sanded smooth first.
    For each set of 2 base pairs you will need:
    ● 4 phosphate
    ● 4 deoxyribose
    ● 15 male bonds
    ● 15 female bonds
    ● 1 of each of the 4 nucleotide bases

    Analysis: After showing the assembly of DNA (Figure 2) and explaining how this encodes information for replication or protein-building, you may include some math if you wish.
    Q: With the number of base pairs in your DNA segment, how many different genes could you have to build different proteins? [Answer: 4^(number of base pairs)]
    Q: If there are 20 different amino acids build (and combined into proteins) what is the minimum size of sequence of base pairs that encodes amino acids? [Answer: 3]
    Q: Plot the number of different genes possible (y) versus the number of base pairs in a gene (x) for several sizes of genes.

    Figure 1: Example of assembly of one sub-unit. Female bonds are 6 mm in diameter and male bonds are 5 mm in diameter to facilitate matching these.

    Figure 2: Assembled segment of DNA with 2 base pairs. Note that scaffold of phosphate and deoxyribose has alternating sub-units and direction is reversed on opposite side.

    posted in Models
  • Crinoid Bio-Medium Aquaculture: Nutrient Flows in Classroom Aquaria

    Crinoid Bio-Medium Aquaculture: Nutrient Flows in Classroom Aquaria
    Purchase access to the 3D stereolithography (.STL) files and accompanying lesson plan for the Crinoid Bio-Medium Aquaculture model!

    Model Price: $2.99

    Hits the Standard: HS-LS2-3: Construct and revise an explanation based on evidence for the cycling of matter and nutrient flow of energy in aerobic and anaerobic conditions.

    Lesson Brief: Producers such as plants and consumers such as fish are important components of many ecosystems. Energy and nutrients flow between them and other components. Providing a substrate, or physical habitat, for another component, decomposers, can increase the efficiency of nutrient recycling. Using a linked fish – plant system, students will add a decomposer element, in the form of nitrate-reducing bacteria, to the system and document how this alters nutrient flow through the system.

    Background: Box and arrow diagrams are used in ecological science to show the magnitude and location of different pools of a nutrient as it moves through a system. The boxes represent different locations, different forms of the nutrient, and different biotic groups in the community as they use the nutrient. Arrows show the flow of the nutrient from one box to another. Together, these form a graphical balance sheet for the nutrient in a given ecosystem.
    Nitrogen is vital to all life. It is an important especially in proteins. When animals break down nitrogenous compounds, they release waste products such as ammonia, NH4. Plants take up nitrogen in the form of nitrates, compounds containing NO3-. In a natural ecosystem, there are many different routes between these forms of nitrogen. In addition to producers and consumers, a functioning ecosystem has decomposers. These organisms break down complex organic matter into simpler forms, and alter the form of nutrients making it available to producers and different consumers. Many decomposers are bacteria that alter ammonia to nitrite, NO2-, and other bacterial species that alter nitrite to nitrate which is then useable to plants. Bio-media provide a physical substrate for bacteria communities that help change ammonia from fish waste into plant-useable nitrate.

    Activity: Print out and assemble several sets of the Crinoid bio-medium model (Figure 1). If two aquaculture set-ups or two aquaria are available, outfit one with a chamber of Crinoids downstream of the existing filter. Leave the other aquarium as it is. Allow the water to circulate as normal for at least several weeks. Using commercially-available test strips, test the nitrogen levels in the tanks. Create a box and arrow diagram for the nitrogen cycles in the two tanks. If only one aquarium or aquaculture set-up is available, test nitrogen levels before using Crinoid media and several weeks after introducing.

    Analysis: Did the ammonia, nitrite, or nitrogen levels differ between the treatments with and without the Crinoid media? Was the surface area provided to the nitrogen-altering bacteria sufficient? After examining the box and arrow diagrams, suggest ways that this system could become more self-sustaining, in other words, require less inputs and removals.


    Figure 1: Assembly of the Crinoid bio-substrate. Print 1 scolex and 16 arms. Glue arms halves together ensuring careful match of halves of pegs. Insert pegs into holes. Printing can be facilitated by printing enough for 1 Crinoid at once, and by ensuring flat side of arms are down. Holes for 4 arms are not visible in the figure.

    posted in Models
  • RE: Teaching Aid Wish List: January 2019

    @JeffHolland @JShukle January's model, Simulating Geological Faults, is now up on our models forum, and available for purchase from The Shape of Science Store!

    posted in Teaching Aid Wish List
  • Mr. Fawlty: Simulating Geological Faults

    Mr. Fawlty: Simulating Geological Faults
    Purchase access to the 3D stereolithography (.STL) files and accompanying lesson plan for this model!

    Model Price: $7.99


    Title: Simulating Geological Faults

    Hits the standard: HS-ESS1-5 Evaluate evidence of the past and current movements of continental and oceanic crust and the theory of plate tectonics to explain the ages of crustal rocks.

    Lesson Brief: The surface of the earth is composed of tectonic plates that slowly move over a molten core. The movement of these plates leads to earthquakes, mountain building events, and band of rock of increasing age as you move away from bathymetric ridges where divergent plate movement causes new rock to be formed. This geological sandbox can be used to simulate faulting in a tectonic plate that can lead to mountain building and earthquakes.

    Background: The movement of tectonic plates causes earthquakes and builds mountains. The upper layers are relatively brittle compared to the lower, hotter, layers. Within the upper layers however, layers of different types of rock vary in how they respond as well. In places where plates are subject to extension forces or tension, faults may develop that interrupt the bands of similar-aged rocks. At the surface, these faults can lead to parallel bands of mountains, as in the ranges east of the Sierra Nevada.

    Example of “geology sandbox” in use:

    1. Print out the Geology Fault Simulator and assemble it (Figure 1). This will require 2 sheets of 3/16” acrylic plastic to act as the clear sides. Dimensions of these clear sides are 7-1/4 inches by 4-3/4 inches. Round the corners for safety. For added realism, bolt a doubled-up Ace bandage to the bottom between the body and moving plate to mimic the ductile mantle layer (Figure 2). If the bandage is used, bolts through carefully drilled holes; screws will split the model.
    2. Fill the fault simulator with alternating layers of different dry materials such as sand, flour, cocoa, and corn meal. Coarser material such as coarse sand is more ductile and is well-suited to the bottom layer, and for acting as a heavy layer at the top. Fine materials will be more cohesive and initiate fault lines. Experiment with different alternating layers.
    3. Tape an acetate sheet to one side of the simulator. Slowly use the screw to pull the plate back to cause tension in the layers. As the faults begin to develop, use a marker to draw the location of the fault on the sheet. Alternately, photograph the simulator and add the fault lines digitally in a program such as Powerpoint. Do this at several points during the experiment


    1. Did faults develop in the layers? How well did this model what happens in actual rock layers under tension? What are the important features of a good model?
    2. Did ridges develop in the surface? How does this simulation differ from the movements of actual tectonic plates? How is it similar?

    Figure 1: Assembly of the 3-D printed parts of the Geological Fault Simulator.
    Figure 2: Installation of acrylic plastic sides. The optional Ace bandage to mimic a ductile mantle layer has been bolted in. It is folded to create a double layer and cut to length.

    posted in Models