BRIEF DESCRIPTION OF MODULES DEVELOPED BY MSSV FOR AFTER-SCHOOL SCIENCE CLUBS
The following modules have been developed by the MSSV for use in after-school science clubs for middle schools (grades 5-7). They usually require about 90 minutes, but some modules could be adapted for shorter in-class sessions.
To make a successful glue bond, an adhesive must wet both surfaces to be bonded and be strong enough to hold them together. This normally involves spreading a liquid adhesive over the surfaces and letting it harden by drying, cooling, or chemical reaction. The students look at each type of hardening process using a water-based wood glue, a hot melt, and a two-component epoxy. Each adhesive will be used to glue together various materials such as paper, aluminum foil, and wood. The students will determine at how quickly and firmly the bonds form and see which surfaces wet with each glue. In addition, each student will test glues between identical wood fixtures that are pulled apart by a chain to determine which is the strongest and weakest.
2. BEHAVIOR OF GASSES
We explore one of the simple gas law relationships, that between temperature and volume. The students use balloons inflated with air. The circumference of the balloon is measured at room temperature, at ice water temperature, and at 45 ˚C. The measurement is made with waterproof nylon twine and a meter stick. The students use the relationship between circumference and volume of a sphere to calculate the gas volume and then plot the results on graph paper.
We discuss why bridges are stronger than the materials from which they are built. A plank across a small stream will not carry much weight without sagging and finally breaking. When the same amount of lumber is built into a simple truss structure, it will carry much more weight safely and sag much less. To demonstrate how this is possible, the students build two simple bridges from soda straws held together with hot glue. The first bridge is a simple slab which will span the space between two stacks of books. The second bridge is a truss structure built from the same materials. The load carrying capacity of both structures will be tested by loading each with a stack of pennies placed at the center of the span until the structure fails.
4. BUILDING A SMALL ELECTRIC MOTOR
The magnetic field surrounding a current-carrying conductor is demonstrated using a large wire and a compass. Then the force on a current carrying conductor in a magnetic field is demonstrated using a simple apparatus. After a brief review of the theory, students divide into groups to build a simple DC motor.
5. DENSITY AND BUOYANCY
The objective is to connect the densities of solids, liquids, and gases to their molecular constituents. Students observe the behaviors of a variety of liquids (water, salad oil, rubbing alcohol) and solids (candles, rubber balls, Styrofoam balls) with special reference to the relationship of ice and water. Water displacement is used to determine the density of irregularly shaped objects. Buoyancy is explored by the construction of aluminum foil boats.
6. DNA EXTRACTION FROM WHEAT GERM
DNA can readily be extracted from cells, like those of wheat germ, by using simple household items such as dish detergent and rubbing alcohol. Before beginning the experiment, the DNA structure and significance is described, including the history of its discovery in the 1950s. In a series of seven steps, the students prepare their wheat germ samples and ultimately collect clumps of tangled DNA molecules that are easily visible to the naked eye. We finish by discussing what happened at each of the seven steps that allowed us to extract the DNA from the cells. We examine real-life applications of the science of DNA extraction.
7. PINHOLE CAMERAS AND CAMERA OBSCURA
We explore the properties of light and optics. We examine what happens when light passes through a very small hole. We discuss what a lens is and what it does to light, whether it is in your eye or in a camera. The students then build simple imaging systems (camera obscuras) out of oatmeal boxes, lenses, and viewing screens. These are miniature devices similar to the chambers used by 17th century artists, such as Johannes Vermeer, as drawing aids. The students are allowed to take their cameras home.
We introduce concepts of performing length and mass measurements and discuss why everyone may not always get the same results. Students will make multiple measurements on small objects using various measuring devices. The results are plotted on distribution curves and the shape of the distribution is noted. The concept of averaging to improve the measurement is demonstrated. Student groups make multiple measurements of the height of one volunteer student that is in both standing and horizontal positions. The use of simple statistical techniques to draw conclusions from the data is shown. Some precision measurement devices are exhibited.
9. HOW BATTERIES WORK
The objective is to illustrate oxidation-reduction chemical reactions that are used in batteries to release electrons that can move into an external circuit. The students carry out a simple oxidation-reduction reaction with an aluminum/silver couple, observe the results, and discuss how this does or does not form a battery. They then prepare a battery with a different metal pair, measure the voltage produced, and demonstrate the battery’s ability to light a small LED.
10. EXPLORING THE BEHAVIOR OF FLUIDS
The objectives are to (1) identify and explore behaviors of fluids and to relate them to the structure of molecules in the fluid, and (2) to react two liquids to form a polymer (glue) and observe its anomalous fluid-like properties. Water is compared to cardboard and modeling clay in terms of its ability to be poured, to assume a shape, and be cut with scissors. A polymer is formed from glue and liquid starch and its behavior is then compared to that of water, cardboard and modeling clay.
We discuss Newton’s laws of motion and have the students build rockets. They learn why rockets have specific structures and weight considerations. They launch their own rockets outdoors and learn how to measure the height of the trajectory. There is a choice of water, paper, or dueling rockets. Data from all the launches is collected, analyzed, and later posted to a blog. (www.rocketclubs.blogspot.com)
We illustrate the utility of simple physical and chromatographic separations. Students begin with a plastic bag filled with a mixture of different beans. They separate the different beans manually and characterize each group in terms of size, shape, color, and weight. Then they perform a separation of liquid colors in marker pens using paper chromatography. They compare different solvents and different brands of marker pens. The importance of the polarity of the solvents, as well as the mixtures of some colors to form others, is discussed.
13. SIMPLE CHEMICAL REACTIONS
We demonstrate chemical reactions using simple, readily available, reactants and explore how the reactants influence the reaction rate. Multiple measurements with each reaction system allow students to learn about averages and the variability of data. By using oxidized pennies and restoring them to a bright shiny condition provides the students with a convenient endpoint for a time-of-reaction measurement. “Penny-cleaning races” compare the rates of reaction with various weak acids: cola, vinegar, and lemon juice.
14. SOUND AND WAVES
The general nature of sound waves is discussed in terms of vibrational wavelength, frequency, and amplitude. We use a PC-based digital oscilloscope and a frequency synthesizer to demonstrate these concepts in real-time. Then the students are encouraged to play musical instruments. The sound is picked up with a microphone and displayed on the oscilloscope, demonstrating harmonics and frequency mixing.
15. DATA ANALYSIS AND STATISTICS
We introduce the use of statistics, averages, graphs, data, and sampling techniques. Each student or team is given a sample (M&Ms or colored blocks) and are asked to guess the number of items in the sample without counting. They count their samples to see if the original estimates were reasonable. Then they sort the sample by color and draw bar graphs to illustrate color distributions. The individual results are then combined, and each group prepares another graph of the overall data. Students will determine if the sequence of colors changed when going from individual data to the larger sample of the overall data. All the samples can be pooled into a bowl, and the students determine which color is the most and the least likely to be selected.
Volcanoes are discussed to help the students understand the geological structure of the Earth in terms of layers, plate tectonics, and volcanoes. We discuss how volcanoes are classified, what materials come out of volcanoes, what dangers they pose, and what benefits they may provide. To demonstrate the action of a volcano, the students simulate eruptions using simple, non-toxic materials such as vinegar and baking soda.
17. HEAT FLOW
We discuss energy and heat, and the mechanisms of heat transfer or loss. This leads to a description of heat conduction and of thermal insulation. The students perform experiments in which they measure the relative insulating properties of several different kinds of cloth and clothing liners. This is done using digital thermometers and stopwatches to measure the rate of heat loss of hot water in cans insulated by samples of the materials. If time permits, they use an electric fan to examine the effect of airflow (wind chill). All the results are plotted on the blackboard and discussed.
18. BLOOD PRESSURE AND BLOOD FLOW.
The mechanism of the human heart and circulatory system is described and the reason for the periodic changes in pressure in the arteries is explained. The terms “systolic” and “diastolic” are explained and the common method for measuring blood pressure is demonstrated and explained. Students are taught how to measure blood pressure on each other. The effect of blood circulation loss is demonstrated by using blood-pressure cuffs to constrict circulation in the arm while the students are working to compress a sponge with the hand. The functions of blood circulation are reviewed and the mechanisms of various failures of that system are explained. This leads to a discussion of heart attacks and what can be done to make them less likely.
19. MUSCLES, NERVES, AND ELECTRICITY
We make the point that our body is full of muscles – not just the ones we always think of. We point out that the skeletal muscles, the heart, and many others are similar. We then discuss how muscles are controlled, and introduce the importance of the brain and the nervous system. We talk about how nerves are similar to and different from electrical wires. We then use a PC-based digital oscilloscope and electrodes to demonstrate muscle reflexes in volunteer students. The students see the complex electrical signal associated with muscle contraction and the simple signal associated with a reflex in the arm or leg. We discuss the difference between a muscle contraction signal from the brain and a reflex from the spinal cord and show them what the electric signal should look like. We then talk about the heart as a muscle and how it is controlled by nerves for both rate and contraction. Student volunteers are connected to chest or shoulder (girls) electrodes to record ECGs. We explain the components of the signals, and print them so that the students can take them home.
20. LIGHT AND COLOR
We seek to reveal the concepts of color through light mixing (additive colors) and filtering (subtractive colors). Also we reveal concepts of luminescence and light absorption. First we discuss white light and the students use gratings to disperse a white light source into a color spectrum. Connections to rainbows and other dispersive phenomena are made. We emphasize that visible light is only a small fraction of the electromagnetic spectrum. Concepts of frequency and wavelength are discussed. The students then perform light mixing experiments with red, green, and blue LEDs to demonstrate additive color through the creation of secondary colors (magenta, yellow, and cyan) and white light. Connections are made as to how the human eye “sees” color, and how a TV screen can “produce” various colors. Finally the students use colored filters to understand the concept of “subtractive” color mixing, and its connection to paints, inks, etc. They will discover a different set of primary colors (magenta, yellow, and cyan) and secondary colors (red, green, and blue).
21. A DAY AT THE BEACH
We introduce a variety of basic scientific principals through the observation, comparison, and analysis of various beach sand samples. The students are taught that a beach can reveal the geology of the area, as well as the dynamics of wind and water flow. They examine sand samples from a variety of land/water junctions including ocean, river, and lakeshore beaches. In the process, they familiarize themselves with the operation of a stereomicroscope and engage in measurement of objects within the microscopic field of view. Discussion of the effects of wind and water on shorelines, erosion and weathering, and changes in current velocity will be exemplified using a variety of sand samples. Students will also be introduced to, or review, some basic mineralogy. Observations and measurements will be recorded on a data collection sheet. Students will leave with one or more sand sample cards containing their choice of sand, and relevant data about the sample.
22. SHAPES IN NATURE
This module explores why things like hair and mineral rocks have their characteristic shapes. We explore how atoms are arranged to give a particular structure, such as six-sided snowflakes or the mineral fluorite. We look at fractal geometry – what it is and where we find examples of fractals in nature, such as in Romanesco broccoli. Finally, we build an origami virus particle to see how nature efficiently packages DNA into these symmetric, infective agents.
23. STUDYING ENVIRONMENTAL VARIABLES WITH BRINE SHRIMP
We introduce basic brine shrimp biology and ecology. Students are involved with a protocol that raises shrimp from eggs through several stages from juvenile to the adult status over several weeks. They use experimental procedures including microscopy to study shrimp behavior over their life stages. The students use hypothesis-driven experimental methods to examine the effects of changes in naturally occurring environmental variables such as salinity and low oxygen concentration on shrimp behavior. They also learn principles of data collection, tabular organization, and qualitative and quantitative analysis.
24. OWL PELLETS
Most owls are predators that feed on small mammals, birds and reptiles. Owls swallow their food whole or in large chunks, but their digestive system cannot digest fur/hair, bones, teeth, feathers, etc. Rather, a portion of the owl’s stomach compresses these parts to form the pellet. The pellet does not pass into and through the intestine of the owl. Instead, the owl regurgitates (coughs up and spits out) the pellet. In addition to bones, teeth and fur an owl pellet may contain the exoskeletons of insects, feathers, fish scales, or various types of seeds. By examining what is found in owl pellets scientists can tell what and how much an owl has eaten and can make predictions about the habitat, environment and behavior of the owl and its food sources. By completing this module a student will gain an understanding of ecosystems and the complex interactions that exist between organisms and their physical and biological environment.
Foldscopes are powerful paper microscopes. https://www.foldscope.com. This module takes two sessions. The first section is putting the Foldscopes together and the second is using them and more on microscopy. The students keep their Folscopes.
26. WIND ENERGY
Wind turbines are used to demonstrate the conversion of wind energy to both electrical and mechanical energy. The students have the opportunity to examine how the number of blades and their angles (pitch) can affect the conversion efficiency to electrical energy by measuring and recording the current generated by the turbines. Similarly, they examine how the same parameters affect the efficiency of mechanical energy generation by examining how fast the turbines lift a specific weight a set distance