Directions: After students have had a chance to review the article “Origami outfits help bots retool,” lead a classroom discussion based on the questions that follow.

The last article-based observation question references the basic, interdisciplinary nature of the origami bot design and construction. After students have read the article, watched the video and completed the first section of questions, you could begin a discussion that allows students to express their own article-related interests. You could also encourage them to explore an idea for a simple project based on their interest. For example, if a student is fascinated by the origami designs of the exoskeletons, allow them to try to rebuild one of the origami exoskeletons and then allow them to try to design their own exoskeleton to perform a different task (see additional Engineering and Experimental Design questions below).  

CHEMICAL SCIENCES

Discussion questions:

1. What is a polymer, and what are some examples of polymers in chemistry and biology?

A polymer is a chemical made of long chain-like molecules which themselves are made up of subunits called monomers. Some examples include polyethylene made of chains of ethylene subunits, polystyrene made of chains of styrene units, polyurethane made of chains of urethane subunits, nylon made of amide subunit chains and polyolefin made of olefin subunits. DNA and RNA are biological polymers made of nucleotide subunits, and proteins are biological polymers made of amino acid subunits. Sugars and lipids can also form polymers. For example, both cellulose and starch are made of glucose subunits.

2. What types of substances dissolve in water? Explain how water dissolves a substance.

Ionic compounds and polar molecules dissolve in water, which itself is made of polar molecules. Polar molecules have an overall neutral charge, but an uneven distribution of electrons between atoms within the molecules leads to partially positive and partially negative charged regions. These partially charged regions attract other molecules and ions with opposite charges. Take table salt, or sodium chloride, for example. Water’s partially negative charged oxygen atoms attract salt’s positive charged sodium ions. Meanwhile, the partial positive charge on water’s two hydrogen atoms attracts salt’s negative chloride atoms. Because of this attraction, when table salt is combined with water, water molecules surround the salt molecules and may completely dissolve the substance.

3. Other than the molecular composition of a solute, what other conditions affect the solubility of a solute and solvent?

Factors that affect the solubility of a solute in a solvent include: the temperature of the solute and solvent, the acidity or basicity of the environments, the amount of solute and solvent, particle size, the amount of applied mechanical motion and, for gases dissolving into liquids, the external pressure of the system.

Extension prompts:

4. What is heat-shrink material made of, and how does it work?

Heat-shrink material is a polymer that has been specially treated during manufacturing. First, the polymer is cross-linked, meaning that covalent bonds are created between different polymer chains. Those cross-links tend to make the polymer stiffer, like how tangling several strings together makes it harder to pull them apart. Then, the cross-linked polymer is heated enough to loosen it up and stretch it to a larger size. Finally, the polymer is cooled in that stretched shape until it is too rigid for the cross-links to pull it back together. (Imagine stretching a rubber band and then freezing it in the stretched state.) When heat-shrink material that has been manufactured that way is finally heated again its cross-links pull it back into its earlier more compact shape. (Likewise, heating up the rubber band that was stretched and then frozen would thaw out the rubber band and allow it to contract again.) For more information on heat-shrink materials, see Hackaday, Heat Shrink Tubing and the Chemistry Behind Its Magic.

PHYSICAL SCIENCES

Discussion questions:

1. What is magnetism? Why are some materials magnetic and other are not?

Magnetism is a physical phenomenon produced by the motion of electric charges that results in attractive and repulsive forces between objects. Moving charges create an electric current, and anywhere there is an electric current, there is a magnetic field present. Atoms have charged electrons moving around them, and that motion, called orbital motion, can give their atoms magnetic fields. Electrons within a material also have a quantum mechanical property called spin, which makes them behave as if they are spinning around like a top, giving each electron a tiny magnetic field. In order for an atom to have a magnetic field, however, the magnetic fields of its electrons must not cancel each other out (point in opposite directions). If the tiny magnetic fields from many atoms in a material line up with one another, they can add together to produce an overall magnetic field. Iron, cobalt and nickel atoms, for instance, have relatively large numbers of unpaired electrons occupying different energy levels — the spins of these unpaired electrons will align and give the atoms an overall magnetic field. (Paired electrons in orbitals cancel each other’s individual magnetic field, so atoms that contain only paired electrons are not magnetic.) When the magnetic fields of many atoms are allowed to align in a material, the overall object has a large-scale magnetic field.  

2. What is a solenoid?

A solenoid is a coil of wire. Passing an electrical current through the coil creates a magnetic field down the center of the coil. The magnetic field can be made stronger if a magnetizable metal (such as iron) core is placed inside the coil, making it an electromagnet.

Extension prompts:

3. How can a solenoid be used to move things?

Using the solenoid as an electromagnet, it can attract or repel other magnets or magnetic metal. Alternatively, the solenoid coil’s magnetic field can be used to exert a push or pull on a magnetic metal core inside the coil, like an electrically operated bolt lock.

3. How can a solenoid be used to make sparks?

Electrical energy from current flowing through the solenoid coil is converted into magnetic energy emanating from the solenoid. If the wire to the solenoid coil is disconnected, the magnetic energy will resist losing the connection, creating a high-voltage spark that jumps to the disconnected wire and tries to keep current flowing.

BIOLOGICAL SCIENCES

Discussion questions:

1. How does an RNA polymerase enzyme adapt itself to make RNA copies of different DNA genes under different circumstances, essentially acting like a natural transformer or origami bot?

RNA polymerase is an enzyme that makes RNA copies of DNA genes. Which genes RNA polymerase copies, when the enzyme copies them and how many copies the enzyme makes depend on various factors sensed by the cell, including what the genes control — cell division, inflammation or hormone production, for example. To do these various jobs under different circumstances, RNA polymerases depend on a collection of protein subunits, transcription factors and regulatory proteins. Called holoenzymes, RNA polymerases will add or subtract these gene-copying helpers based on signals from the cell, similar to how the origami bots can change their exoskeletons based on the task at hand.

Extension prompts:

2. How do macrophage and mast cells, certain types of white blood cells in the immune system, adapt themselves to detect different intruders in your body?

Antibodies are proteins shaped like two-pronged forks; the tip of each prong has a specific shape to bind to a particular pathogen (germ) or allergen (something that your body should not react to, but does). Antibodies are made by one type of white blood cell, B lymphocytes. But other types of white blood cells, such as macrophage and mast cells, can also pick up and use those antibodies. The back end of the antibody (called the Fc domain) plugs into a socket (called the Fc receptor) on the surfaces of macrophage and mast cells. Using those plugged-in antibodies, macrophage and mast cells can adapt themselves to detect whatever pathogens or allergens the antibody tips selectively bind to. When macrophage cells detect a pathogen that way, the cells try to eat it to destroy it. When mast cells detect an allergen that way, the cells release histamine, which causes inflammation (which is why you take an antihistamine if you have an allergic reaction).

3. How do complement proteins act like a swarm of self-assembling nano-robots?

Complement proteins are another part of the immune system. Complement proteins bind to intruders in your body, but not to cells or other normal components in your body. When some complement proteins bind to an intruder, they attract more and more complement proteins, producing a swarm that attacks the intruder (the membrane attack complex) and release complement protein fragments that attract other parts of your immune system.

ENGINEERING AND EXPERIMENTAL DESIGN

Discussion questions:

1. What improvements would you like to see made to the origami robot research?

Robots that can do more themselves without being dependent on externally controlled heating pads to fold the origami materials, water to detach itself from an origami exoskeleton or solenoids to move the robots. Also, robots with sensors added so the bots can detect and respond to stimuli instead of having to be guided by human operators for every step.

Extension prompts:

2. What are some possible extensions and applications you can think of for remote-controlled magnetic manipulation?

Precise remote-controlled magnetic manipulation of objects for surgery, repetitive lab experiments, manufacturing, printing and food harvesting and processing are a few possible examples.

3. What are some possible extensions and applications you can think of for the origami materials?

Origami materials for sensing heat and moisture; changing your clothing for appearance, function or in response to changing environmental conditions; changing your vehicle or your home for appearance, function or in response to changing environmental conditions.

4. What are some possible extensions and applications you can think of for such robot research?

Robots that configure themselves for surgery, for finding people in collapsed buildings, for space exploration or even for cleaning your house.