Teaching circuits to students
Electricity can be a complex and imposing topic to present to your students. Before we talk about circuits, let’s go over a few definitions:
- Load – A device that does work or performs a job (i.e., the light bulb in our circuit).
- Electrical current – The flow of electrons from an area of high concentration (“a lot”) to an area of lower concentration. *Note: the negative side of the battery has a high concentration of electrons.
- Electron –Â A negatively charged particle that orbits the nucleus of an atom.
- Generator – A device that converts mechanical or chemical energy into electricity. Wind, water or an engine can power a generator.
- Electrical circuit – An electrical path that is closed (all parts connected), allowing the electricity to return to the original source (the battery).
- Parallel Circuit – A circuit in which the components are connected like a ladder. This circuit splits the voltage equally to all of the components.
Creating a Simple Circuit
- Place a “D” cell battery in a battery holder. The battery holder will allow you to attach wires with alligator clips to the positive and negative ends of the battery.
- Now, screw a small light bulb (mini lamp) into a lamp holder. Like the battery holder, the lamp holder will allow you to attach alligator clips to the light bulb (your load).
- To complete the circuit, you will need two wires with alligator clips. Use one wire to connect the negative side of the battery to the lamp holder. It does not matter which side of the lamp holder the wire is attached. Connect the positive side of the battery to the lamp holder using the second wire. This wire will attach to the opposite side of the lamp holder. The light bulb should be lit.
Remember, the voltage of the battery and light bulb should be similar. If the battery voltage is too much larger than the voltage capacity of your bulb, the bulb will burn out. A “D” cell battery provides 1.5V.
Simple Circuit with Switch
Adding a Knife Switch to a Simple Circuit
We will modify our simple circuit described above to complete this task.
- Disconnect the alligator clip that is attached to the negative side of the battery and re-connect it to one side of the knife switch. Make sure the knife switch is in the upright position.
- Take a separate wire and connect the negative side of the battery to the knife switch. Notice that the light is off.
- Lower the arm on the knife switch to connect the circuit and light the bulb.
The knife switch allows you to discuss breaking the circuit and stopping the flow of electrons.
Heath Scientific provides a kit called “Making Circuits Simple” that includes all of the components described in this article. It’s an easy, all-in-one kit to demonstrate circuits to your students.
In this experiment, we are going to determine the effect of temperature on water absorption in warblettes.
To complete this experiment, you will need the following:
1. Create an ice bath by placing a mixture of water and ice in the 500 ml beaker. Fill approximately 1/2 full.
2. Using a graduated cylinder, pour 50 ml of water into one of the 250 ml beakers. Place the beaker in the ice bath. This will keep the water cold during the experiment. For theÂ purpose of this experiment, it will not be necessary to measure the actual temperature of the water. Our main goal is to compare cold and warm temperatures in general. The water will drop to between 5 and 10 degrees celsius.
3. Using a 50 ml cylinder, add 50 ml of hot tap water to the second 250 ml beaker. The water temperature will be approximately 40 degrees C and will continually cool during the experiment.
4. Add 40 Warblettes to each of the 250 ml beakers. Allow the Warblettes to absorb water for 20 minutes.
5. Take one beaker and pour the remaining water into the graduated cylinder. Measure this amount and subtract from the original 50 ml. This calculation will give you the amount of water absorbed by the Warblettes. Repeat this step for the second beaker.
The warmer temperature water will promote faster growth of the polymer. Compare this to real life applications like:
- Coffee, tea, sugar, and other solids dissolve faster in hot water.
- Most bacteria grow best at warmer temperatures (close to human body temperature).
- Ice on a contusion reduces bruising by slowing blood flow.
Warblettes can be used in many experiments and create interest and excitement while reinforcing scientific principles.
Sodium Bicarbonate, Calcium Chloride and Phenol Red
Let’s go over the procedure first and then we will discuss what is happening.
1. In a quart baggie, place sodium bicarbonate(1 tsp) in one corner and calcium chloride(1 tsp) in the other.
2. Lay the bag on its side and place a small cup (medicine cup size – 1 oz) of phenol red in center of the bag. Be careful not allow the any on the chemicals to mix yet. Seal the bag
3. Gently pour the phenol red where it spills into each corner. Do not mix the two corners yet.
4. Have the students feel each corner and make observations. Continue the observations for a few minutes.
5. Pick the bag up and gently move the bage side to side, mixing the chemicals. What happens?
The side of the bag with calcium chloride becomes warm. The calcium chloride dissolves forming calcium and chloride ions. The release of heat (exothermic) is a result of the calcium chloride dissolving and not a chemical reaction.
When the sodium bicarbonate dissolves to form sodium, hydrogen and carbonate. It becomes cool (endothermic). The baking soda absorbs heat in order to dissolve. This is not a chemical change.
When the two sides are mixed, calcium carbonate is formed which is insoluble. Also formed are water and carbon dioxide. The carbon dioxide (gas) causes the bag to inflate. When the carbon dioxide dissolves in the liquid, carbonic acid is formed. This change in pH causes the phenol red to turn yellow. A chemical change has now occurred.
Remember to have the students use all lab safety measures. If the bag becomes over inflated, release some of the gas.
The interest in renewable energy has increased greatly. The US currently produces enough wind energy to power 14 million homes. Approximately 2% of our energy comes from wnd, which is double from just 3 years ago. many beleive that in 2030, 15-20% of our energy will come from wind.
The reason for the growth is partially associated with new government regulations concerning our impact on the environment. Federal and local governments are receiving pressure from voters to find alternative sources. Experts believe that if the 2030 scenerio occurs, we would reduce carbon dioxide emissions by 7600 metric tons and create 200,000 jobs.
Windmills have been around for centuries to pump water and grind seeds into grain. A wind turbine is an advancement that turns an electrical generator. The force of the wind, turns the blades. the rotor turns and spins a driveshaft that is connected to an generator. the generator converts this mechanical energy in to electrical energy.
There are several variables that determine the amount of energy produced: wind speed, diameter of the rotor, density of the air, and efficiency of the turbine.
A great product for teaching wind power concepts is the Basic Turbine. The Basic Turbine is a great start for teaching about wind energy in the classroom. Visit www.heathscientific.net to purchase this item. This is the most affordable and robust wind turbine kit on the market. Design blades and test your power output with a multimeter, LED bulbs, or an ultra capacitor.
The instructions that are included will show you how to build this PVC turbine, how to make blades for your wind turbine, how to use a multimeter to record electrical data and will discuss some basic wind energy science.
In School Science Store
With the reduction in state funds, the need to raise money through other methods has become even more important. Science is a subject that can’t be fully appreciated when limited to text books and worksheets. One of the keys to teaching young students is camoflage. When the student is engaged, enjoying the activity, creating and problem solving, they forget that they are supposed to be learning. These instances are where some of the greatest lessons are learned.
When approached properly, science is easy to make interesting……but it isn’t free. The students benefit greatly from using real science equipment, beakers….graduated cylinders…microscopes….live animals…pipets and test tubes. As educators, one goal should be to create young scientists and prepare them for the world they will find.
I often hear that “My school can’t afford these items.” With some hard work, outfitting a science lab can be achieved. Heath Scientific has been providing fundraising options to teachers, PTO’s and school organizations for 10 years. Create excitement and interest in your science program by setting up an Exploration Fair. Your school will ask volunteers (parents are great resources) to help run a retail store for a week. The store has science experiments, rocks, fossils and educational toys that excite the students and raise funds for your school.
Set up an online store at error and encourage students and parents to visit the site for birthday and christmas presents or for science fair projects. The items are shipped directly to the customer and you do not have to distribute any merchandise. Your organization receives a percentage of all sales.
Heath Scientific also provides bulk packages that allows your organization to make up to 80% profits. Use the profits earned to buy real science equipment that can be used for many years.
Don’t let money stop you from providing your students a top notch science classroom.