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Circuit Diagrams and Ohm’s Law on Paper

SP-ENGR-007 · Grades 9-12 · 50 minutes

Teacher directions only. Student worksheets and the answer key are in the complete teacher PDF. This downloaded guide opens offline.

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Career and Technical Education · Engineering / Robotics / Industrial Technology
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Page 2
Circuit Diagrams and Ohm’s Law on Paper
Career and Technical Education · Engineering / Robotics / Industrial Technology · Grades 9-12 · 50 minutes
Time needed
50 minutes (one class period)
Prep
Copy the 2-page worksheet (one per student). Write the three formulas listed in the steps on
the board.
Technology
None. Calculators are optional.
Student
independence
High. Students work alone, then check with a partner.
Copies to make
One 2-page worksheet per student
Materials
Pencils, Worksheet, Whiteboard or chalkboard, Calculators (optional)
Goal for today: Students will identify common circuit symbols and will use V = I × R, series and parallel resistance
rules and P = V × I to solve problems.
Before the bell
☐ Copy the worksheet, one per student (2 pages).
☐ On the board write: V = I × R. P = V × I. Series: R total = R1 + R2 + R3. Two parallel resistors: 1/R total =
1/R1 + 1/R2.
☐ This is a paper-and-calculation lesson. Students must NOT use any batteries, wires, outlets, chargers or
electrical equipment today.
☐ Keep the answer key (page after the worksheet) on your desk.
Say this to start
Good morning! Today is electrical engineering on paper. Electricians and engineers read circuit diagrams, which use
simple symbols for each part. You will learn the symbols and use a few formulas to figure out how much current flows
and how much power a circuit uses. Nobody will touch any wires or batteries. The formulas are on the board, and every
answer should have a unit.

SubstitutePlans.com
Career and Technical Education · Engineering / Robotics / Industrial Technology
SP-ENGR-007 · Free to print and use in your classroom · substituteplans.com
Page 3
Run of show
Minutes
What you do
What students do
0–5
Take attendance the way the school requires. Hand out the
worksheet.
Settle in and take out a pencil.
5–14
Read the passage aloud. Use the board example: “12 V
across a 6 Ω resistor gives I = 12 ÷ 6 = 2 A.”
Follow along and copy the three formulas.
14–21
Tell students to complete the symbol-matching section
(questions 1–6).
Match each symbol description to its part.
21–40
Tell students to complete questions 7–15 in the work
boxes. Walk around and check units.
Use Ohm’s law, series and parallel rules
and the power formula.
40–46
Tell students to finish questions 16 and 17. Let partners
compare answers.
Answer a true/false and a short question
about how circuits are wired.
46–50
Collect all worksheets and put them in a stack for the
teacher.
Hand in the worksheet.
If things go wrong
• If students ask what the symbols look like, tell them the worksheet describes each one in words and they can
sketch it in the margin.
• If students get confused by parallel resistance, point out that a parallel total is always smaller than the
smallest single resistor.
• If a student asks to test a real circuit, remind them that today is paper only and nobody should touch any
outlets or electrical equipment.
• If a student finishes early, check that every answer has a unit (V, A, Ω or W), then use the early finisher list.
Early finishers
• Sketch a circuit diagram with a battery, a switch and one lamp, labeling each part.
• A 40 W lamp runs at 120 V. Use P = V × I to find its current (about 0.33 A).
Support and challenge
• Support: Let students use a calculator and complete only questions 1–8, 10 and 16–17.
• Challenge: Ask students to find the total resistance of a 10 Ω and a 15 Ω resistor in parallel (6 Ω) and the
current from a 12 V source.
Notes for the teacher (you fill this in)
Jot a few lines before you leave. A full Daily Sub Report is in the free Sub Survival Kit at SubstitutePlans.com.
How far the class got / what to pick up next:
Students who were especially helpful: