Grade 9 Applied Science (SNC 1P), Electricity Unit
Overview: Students watch the teacher demonstrate the OJ powered clock. The teacher guides students to wonder what they could change to make the clock work. They do some brainstorming and then the next period, they try it out themselves. There are some optional pre-lab activities that the students could do to explore how to change variables and teachers may want to incorporate post-laboratory literacy activities about alternative sources of energy (optional).
Inquiry Focus: Electricity, electrolytes, electrodes, electrons, current, voltage, voltaic cell, battery
How can I make the OJ powered clock function without using orange juice?
Can I use different metal electrodes (instead of Mg and Cu) and still generate voltage?
Timeline: This series of lessons is to be used partway through the Electricity unit, partway through Current Electricity, after students have learned about current, potential difference and resistance. The teacher can draw on prior knowledge of the Chemistry unit as there is some Electrochemistry involved. The demonstration can be done at the start of one period to jump start the student’s Initiating and Planning (I&P) stages, using a modified Smarter Science Framework approach. This would not take the whole period. Once the brainstorming has occurred a list of materials will be formed, some of which the teacher will bring in and additional resources can be brought by the students (if they wish). A second full period (may be the next day or a couple of days later) will be required for the students to pursue their own questions. Additional time may be given for writing up the lab report if the teacher wishes. Generally, I try to earmark 1.5 periods for academic classes and perhaps 0.5 period more for an applied class (if needed). Students find the concept of making a clock function with OJ (or a potato or a lemon, etc) amazing! Some students will need extra support to help with setting up the voltmeter correctly and reading it. An additional period can be set aside for one of the two literacy tasks.
General Timeline: 1.5-2.5 periods
Half a period is needed for the OJ Clock demonstration and the initiating and planning process, another period is needed for the student inquiry (another 0.5 period may be needed for the completion of the write up). More time would be required if the class does one of the literacy tasks. Another 0.5 period would be added if the teacher chooses to do one of the Skill Builders (Penny Drop or Alka-Seltzer Challenge).
- Electricity is a form of energy produced from a variety of non-renewable and renewable sources.
- Static and current electricity have distinct properties that determine how they are used.
E2.1 use appropriate terminology related to static and current electricity, including, but not limited to: ammeter, ampere, battery, conductivity, current, energy consumption, fuse, kilowatt hours, load, ohm, potential difference, resistance, switch, voltmeter, and volts [C]
E2.2 use an inquiry process to determine and compare the conductivity of various materials (e.g., metals, plastic, glass, water) [PR, AI]
E3.3 identify the components of a simple direct current (DC) electrical circuit (e.g., electrical source, electrical load, switch, fuse), and describe their functions
E3.4 identify electrical quantities and their symbols (e.g., electric current I, potential difference V, resistance R), and explain how they are measured using an ammeter, a voltmeter, and a multimeter
E3.5 explain the characteristics of electric current, potential difference, and resistance, in simple series and parallel circuits
E3.6 describe, qualitatively, the interrelationships between resistance, potential difference, and electric current, in a series circuit (e.g., the effect on current when potential difference is changed)
Strand A – Scientific Investigative Skills
A1.1 formulate scientific questions about observed relationships, ideas, problems, and/or issues, make predictions, and/or formulate hypotheses to focus inquiries or research
A1.2 select appropriate instruments (e.g., soil sampling instruments, a pneumatic trough and test tubes, magnifying lenses, an electroscope) and materials (e.g., ebonite rods, star charts, oxygen testing splints, pH paper) for particular inquiries
A1.3 identify and locate print, electronic, and human sources that are relevant to research questions
A1.5 conduct inquiries, controlling some variables, adapting or extending procedures as required, and using standard equipment and materials safely, accurately, and effectively, to collect observations and data
A1.6 gather data from laboratory and other sources, and organize and record the data using appropriate formats, including tables, flow charts, graphs, and/or diagrams
A1.8 analyse and interpret qualitative and/or quantitative data to determine whether the evidence supports or refutes the initial prediction or hypothesis, identifying possible sources of error, bias, or uncertainty
A1.9 analyse the information gathered from research sources for reliability and bias
A1.10 draw conclusions based on inquiry results and research findings, and justify their conclusions
A1.11 communicate ideas, plans, procedures, results, and conclusions orally, in writing, and/or in electronic presentations, using appropriate language and a variety of formats (e.g., data tables, laboratory reports, presentations, debates, simulations, models)
A1.12 use appropriate numeric, symbolic, and graphic modes of representation, and appropriate units of measurement (e.g., SI and imperial units)
Key Concepts: Voltage, alternative forms of energy
Prior Skill Sets:
- How to read a voltmeter
- Knowledge of how to use Excel or Google forms for graphing or how to do graphing by hand (scaling the axes are sometimes challenging for applied level learners).
- Prior Knowledge:
- How to set up an electrical circuit and read a voltmeter.
- Knowledge of controlled variables, independent and dependent variables.
Materials and Equipment:
Materials for the Teacher:
- Analogue Clock – with hands (without the battery in it)
- Beaker (400 mL) or jar with clamps from Electrochemical set
- Two electrical leads (with alligator clips)
- Two electrodes (Copper and Magnesium ribbon, curled in a spiral)
- Orange juice (one 200 mL juice box is convenient)
- Adobe Sparks Instructional video (1 minute)
Materials for the Students (will vary depending on their choices):
- Voltmeter (preferred since one does not always generate enough voltage to make the clock work) or battery operated clock (without the battery)
- Two electrical leads (with alligator clips)
- Variety of metal electrodes (such as tin, zinc, carbon, nickel)
- Will vary but may include: Citrus fruit (lemons, limes, grapefruit), different juices from concentrate or freshly squeezed, different types of cola or electrolyte drinks (such as Gatorade), potatoes, drink crystals, milk, chocolate milk, vinegar, etc.
- 2-3 Beakers of different sizes (250, 400 mL) per group
- Graduated cylinders for measuring volumes of electrolytes (50 or 100 ml) per group
- Graph paper
- Students may be tempted to consume food materials so teachers should instruct them not to do so. Safety goggles are not needed, since all materials are food items. If the teacher should want to include other acids and bases that are not food items, then the wearing of goggles must be enforced.
Instructional Planning and Delivery:
Day 1 (0.5 period): Demonstration, Brainstorming and Literacy Task + Skill Builder (30 minutes)
Students will be shown a demonstration – the Orange Juice Clock – and asked to generate questions. They will generate, “I wonder” questions. I wonder…what would happen if I use grape juice instead of orange juice? I wonder if it will still work if I used a nickel instead of the magnesium ribbon. Can I make a change that will reverse the direction of the clock hand? The teacher will lead them through the Smarter Science method, generating variables and selecting one to change (the independent variable), one to measure (the dependent variable) and the rest to control (keep the same). Students, working in pairs, will generate a list of materials needed and the second day students will conduct the inquiry. Teachers should also spend some time reviewing with the class how to connect a voltmeter within a circuit. Since this would not take all period, teachers may plan to use a short Skill Builder (Penny Drop or Alka-Seltzer Challenge) which would take about 30 minutes.
Day 2 (full period) : Inquiry Day
The students use gathered materials to collect data. Teachers bring most of the materials and students can bring unusual materials from home (optional). This might be a good time to review how to connect up the voltmeter to the electrodes. The teacher can have some batteries on hand to show students how to connect and read the voltmeter.
Day 3: Laboratory Write up – In the Computer Lab
Students work together (groups of 2-3 are recommended) to complete the narrative lab report or Smarter Science booklet. Students who finish early can work on one of the literacy tasks (Moser Light Bulb or Gravity Light).
Day 4 (optional, full period) – Literacy Task
Additional items that can be added include a literacy task about electricity (about the Moser Light Bulb or the Gravity Light). Students can hand in a Smarter Science booklet or a Four Question narrative report (What did I look for? What did I find out? How did I find it? What did it mean?).
Student Support Resources:
- Adobe Spark instructional video of how to do this inquiry
- Student handout (modified from Smarter Science Framework)
- Literacy tasks (2) –Moser light bulb and Gravity light
Related Background Resources and/or Links:
1. “Citrus Battery Contest.” Citrus Battery Contest, Flinn Scientific, www.flinnsci.com/citrus-battery-contest/dc10830/.
2. The website below has a nice extension, in which lemons are placed in series for a greater amount of voltage.
“Electra the Lemon Powered Battery.” University of Manitoba Outreach, University of Manitoba, www.umanitoba.ca/outreach/crystal/Grade+9/Cluster+3/S1-3-13+-+Electric+Lemons+-+Demonstration+and+Investigation.doc.
3. This Science Buddies website has a fun, easy to follow procedure and materials that uses a lemon and one of the electrodes is an aluminum strip.
Marks are indicated on the modified Smarter Science student handout.
One or both of the literacy pieces can be assessed – see Moser Light document or Gravity Light document.
Try using different fruits in series. Instead of using a voltmeter, students can use LED lights. Or, they can use both. Students would enjoy using the LED lights but they will not light up at lower voltages.