🎯 WALT & Success Criteria

WALT (We Are Learning To): Investigate how changing resistance affects the electric current in a series circuit using a variable resistor.

Success Criteria — I can:

☐   Set up a simple series circuit safely using a power source, ammeter, bulb, and variable resistor.

☐   Read an ammeter accurately and record current measurements in amperes (A).

☐   Describe the relationship between resistance and current using evidence from my results.

🧪 Objective

To measure how the electric current in a series circuit changes when a variable resistor is adjusted, and to identify the relationship between resistance and current.

🛠️ Materials Needed

• 1 x battery pack (4.5 V or 6 V)    • 1 x ammeter    • 1 x light bulb (globe)
• 1 x variable resistor    • Connecting wires    • Switch

🔌 Circuit Diagram

The circuit below shows how to connect your components in series. Draw or label the components as instructed by your teacher.

Label the following on your diagram:   Power Source  |  Switch  |  Variable Resistor  |  Ammeter (A)  |  Light Bulb

📋 Step-by-Step Procedure

Step 1: Set up your series circuit following the diagram above. Ask your teacher to check it before switching on.

Step 2: Adjust the variable resistor to its maximum resistance. Turn on the switch.

Step 3: Read the ammeter carefully. Record the current (in amperes) in the results table below.

Step 4: Gradually decrease the resistance of the variable resistor. After each adjustment, record the current reading.

Step 5: Observe the brightness of the bulb each time you adjust the resistance. Note your observations.

📊 Results Table

Record your measurements in the table below. Write the current reading from the ammeter for each resistance setting.

| Resistance Setting (Ω)  | Current Reading (A)  | Bulb Brightness (bright / dim / very dim) |
|————————————|————————————|————————————————————————————|
| Max Resistance                    | _______________       | _________________________________________|
| Medium Resistance                    | _______________       | _________________________________________|
| Low Resistance                    | _______________       | _________________________________________|

📝 Analysis Questions

When resistance decreases, the current in the circuit _________________ because _______________________________________.

🌟 Extension Activity

Challenge: Look up Ohm's Law (V = I × R). Use the voltage of your battery pack and one of your resistance values to calculate the expected current. How close was your measured result?

♿ Differentiation & Support Notes

🔵 For students who need extra support:

• Work with a partner to set up the circuit.   • Use a pre-drawn circuit diagram to label rather than drawing from scratch.   • Focus on completing the results table and Question 3 only.

🟢 For dyslexia-friendly access:

• This worksheet is best printed on cream or light yellow paper to reduce visual stress.   • Use a font such as OpenDyslexic or Arial (size 14+) when printing digitally.   • Allow verbal responses recorded by a scribe or voice recorder for analysis questions.

🟡 For English Language Learners:

• Key vocabulary: current, resistance, ammeter, variable resistor, series circuit, ampere (A), ohm (Ω) — ask your teacher for a glossary card.   • Draw diagrams or use arrows to support written answers.

🔴 For advanced learners:

• Complete the Extension Activity above.   • Design your own investigation: What happens to current if you change the voltage instead of the resistance? Write a hypothesis and plan.