Interviewing the Experts I find physical science to be the most difficult content I teach–because I understand it the least. Fortunately, there are two physics professors in my family who generously shared their expertise and time with me, giving me big ideas, metaphors, background knowledge, and lots of demonstrations for developing student understanding and my own. Be sure that you are always asking the experts in your life and your community for ways to enrich and deepen your own understandings and teaching practices–people doing the work are amazing resources. And if you are in the area, be sure to keep the Ohio University Physics & Astronomy Department in mind as a resource, as they have an annual open house with amazing labs, lectures, and demonstrations that are appropriate for the whole family.
Big Understandings: These are the big picture understandings that we want to support our students as they develop as they study physical science. Some of these are taken directly from Ohio’s Science Standards for 4th grade, but others come from the physicists I worked with who pointed out essential concepts, frequent misconceptions, and general physical principles that are important building blocks of scientific literacy.
- There is a microscopic world of parts that make up all matter. The parts that make up matter are moving or vibrating even when we can’t see it. Act out water molecule with fists out at about 120 degrees on each side; chest = Oxygen slightly negative charge; arms = Hydrogen slightly positive charge. Have students model how they would move as an H2O molecule (spinning away from each other in gas form; gently coming together and moving away in liquid form; rigidly stuck together in solid form). Then act out how water could surround a sugar molecule in a mixture–both before, as a hypothesis, and after making sugar water mixture, in order to revise their hypothesis based on what they observed.
- Matter can change form, but doesn’t lose mass. Mass can neither be created or destroyed. The sum of the parts = the whole. In a mixture, the parts put together = the whole. Have students design demonstrations of this. For example, they can weigh elements in a mixture and then weigh the material when mixed. Or dissolve a measured amount of salt in water and then let the water evaporate and re-measure the salt. When matter changes form, some may turn into energy. You can demonstrate this by measuring water, freezing it, and then boiling the ice cube in a pan but keeping a lid on it to capture the steam. When the water cools, re-measure.
- Our senses make us big measuring instruments of energy (our eyes measure light and electrical energy, our ears measure sound energy, our sense of touch can measure heat energy).
- Energy moves in waves and naturally moves downhill. Help students understand that energy moves in waves by looking at interference patterns: look at what happens when you put water in a wide, flat bottomed bowl and add movement; look up at a light between two fingers–let them get really close without touching and notice what look like black lines; experiment with tuning forks. Here is a supplemental article that explains light energy a bit more in depth.
- Heat energy can be added or removed. Insulators and conductors are materials that react to heat energy differently. Students intuitively know by the middle grades that some things conduct heat efficiently and others don’t. Have them brainstorm things that they wouldn’t ever touch when hot; then have them brainstorm things that they would use to hold or move hot things. Guide them to generalize the kinds of things that are conductors and those that are insulators. Do research together to uncover misconceptions and confirm understandings.
- Electricity moves through a circuit. If the circuit or loop is incomplete, electricity cannot move through it. Imagine that a strip of metal wire is actually a tube of electrons that function like a tube of water: a tube of water when tilted down on one side will pour downwards; a metal wire filled with electrons will function similarly–add electricity and it will pour down.
- Energy can change form and can be transferred from place to place. Electrical energy can be transformed into light, heat, sound, or magnetic energy. Energy can neither be created or destroyed.
- Magnetic energy and electrical energy are related: electric wire can have magnetic properties and vice versa.
- Magnets are the effect of an electron’s spin–they may repel or attract; magnets are one of the basic forces of nature. For kinesthetic understanding, have students spin either together or apart; same direction or different to show the properties of attraction or repulsion.
- There are contact forces (friction, normal forces) that rely on immediate proximity and action at a distance forces (gravity, electrical, magnetic).
- Speed is the rate at which an object moves. Velocity is the speed + the direction of an object. Acceleration is a change in velocity. Acceleration can be a change in speed or direction– a force must act upon an object for acceleration to occur.
Demonstrations, Experiments, Tools, and Activities for Developing Understanding: Try some of these to help your students develop the creativity and wonder that will help them get at the kinds of physical laws that surround us but are not immediately visible. Guide your students to wonder and extrapolate and attempt to explain what they see.
- What happens when you create some kind of disorder in a substance? Drop ink or food coloring into a glass of water. Observe, discuss, and annotate.
- Add sugar to water, creating a mixture a bit at a time. Observe how light travels through the mixture. Watch the sugar as it’s added. What do you notice about the movement. Make some predictions about what will happen as you continue to add sugar. Revisit having students act like water molecules and surrounding a sugar molecule. Revise predictions as needed. Test and discuss. Watch this video for an explanation.
- Make different colors of jello in clear plastic cups. Use a laser pointer to see if light will pass through the jello. Make predictions before testing each color. Try it in the light and in the dark. Check out this video for an example and explanations:
Caution: always have adults use a laser pointer and give careful safety warnings about the dangers of looking directly at lasers or pointing one at someone’s eyes.
- Try this “unmixing” demonstration:
Have students play around with mixing food coloring into water. Ask them if they they think it can be unmixed–how would they do it, if so? Complete the demonstration and discuss. One of the fun things about this demo is that people are still trying to understand why it works. Pretty fun!
- This disruption demo with milk, food coloring, and dish soap is one that I first saw at a NASA conference for teachers. Try it in class (be sure to use whole milk) and discuss why it works.
- Get a some linear polarization filters to illustrate that light energy moves in waves. Give students an opportunity to play around with them after guiding them through some demonstrations like this:
- Can you make something roll uphill? Pose that question. Then show students the short video. See if they can design something that will allow this counterintuitive event to happen. Here’s a site that might help.
- Ask students how big of a mirror they need to see their entire body. Discuss. Then use some mirrors of different sizes to experiment. Have them work with a partner to see what other factors influence the answer. Have them draw diagrams that illustrate their thinking and hypothesize about why they think their conclusions are correct.
- Everyday Physics Diagram: have students make sketches as they observe in different places that they label with physics that they know. You can use this as a pre-assessment, midpoint assessment, and final assessment to see how what they know about matter and energy has changed and developed.
- Magnet lab: use a variety of sizes, shapes, and strengths of magnets and allow students to explore. Encourage them to explore the magnetic properties of a variety of materials. Include matchbox cards and see if students can develop a track that allows them to race the cars only using magnetic energy.
- Static electricity experiments: have students blow up balloons and then create a static electricity charge by rubbing the balloon on their hair. Then see what they can move with that electrical energy: can they roll empty aluminum cans? Can they create an obstacle course? Go up a ramp? Can they blow bubbles on a pan in dish soap using a straw and then use the static electricity to drag the bubbles? Check out this video:
Give your students a group of materials like the ones used in this video and let them experiment.
- Try making paper circuits, using copper tape, LEDs, and 3V coin cell batteries. This pdf from exploratorium has simple directions with lots of suggestions for adding complexity.
- Invest in Snap Circuits if you are able. There are a number of great Snap Circuits kits that enable kids to build all kinds of electrical circuits and experiment with light, sound, motion, and even ways to access alternative energies, depending on the kits you buy. They’re a great way for kids to experiment with circuits and energy safely and independently.
Big Questions for Pondering & Trying;
- What could be going on inside that means I observe this on the outside?
- What impact do forces of gravity, friction, electricity, and magnetism have on matter? Why do they do what they do? How can we predict what they will do? How can we change them?
The Integrated Curriculum Classroom 