Water Level Display Kit

Classes 9-10, typical ages 14–16. Age ranges vary by learner. Guided low-voltage electronics.

Activity engagement

75–105 minutes. Explore 15–20 min · Build 25–35 min · Test and discuss 35–50 min. Estimated time for building, testing and discussion.

What you need

A computer with a USB port and Arduino IDE is required and is not included.

Included components

• Small Breadboard / Mini Solderless Board - 400 points — 1 breadboard
• Jumper Wire Combo - Male to Male, Male to Female and Female to Female Breadboard Connecting Wires (10 Qty Each) — 1 set
• Illustrated Activity Guide and Observation Sheets — 1 set
• Fitted Headers and Labelled Connection Leads — 1 set
• Arduino Uno R3 CH340G version compatible Arduino Development Board — 1 controller board
• USB A to B Programming Cable for Arduino Uno/ Arduino Mega — 1 data cable
• Water Level Depth Detection Sensor Module For Arduino — 1 sensor module
• 0.96 inch Monochrome OLED Display (SSD1306) — 1 display module
• Bidirectional 3.3 V / 5 V I2C Level Shifter — 1 level-shifter module

What you learn

• A wet contact area changes a resistive sensor signal.
• Calibration maps two reference readings to a relative scale.
• Water composition and corrosion limit repeatability.

Connection guide

• Water sensor labelled + → 5 V; − → GND; S → A0. Keep its connector and electronics above the water.
• OLED VCC → Uno 3.3 V; GND → GND. I2C level shifter LV → 3.3 V, HV → 5 V, common GND; Uno A4/A5 → HV1/HV2, OLED SDA/SCL → LV1/LV2.

Steps to make it

1. Disconnect all power and identify the supplied part labels and pinouts before wiring.
2. Connect the dry sensor and OLED and upload the sketch.
3. Note dry and safe wet-reference raw readings, keeping water below the marked trace limit.
4. Enter those two values as dryRaw/wetRaw and re-upload.
5. Compare four immersion depths, then disconnect power, rinse the sensing end and dry it.
6. Change only the named parameter for the extension, repeat the controlled trials, save observations and disconnect power afterward.

Programming resources

Arduino IDE: select Arduino Uno and the USB port. Use the supplied USB data cable. Serial Monitor/Plotter: 115200 baud.

Libraries to install

• Adafruit GFX Library
• Adafruit SSD1306

Download starter sketch

Test challenge

Compare the same marked depth on three repeats; do not interpret the relative percentage as tank volume.

Observation task

Immersion mark, raw value, scaled percentage and repeat variation.

Expected result

The screen shows a calibrated relative contact level; the reading depends on water conductivity and geometry.

If it does not work

Recalibrate if the water changes. Protect the board/USB connection from splashes and avoid prolonged probe energisation.

Try next

Draw a calibration curve for a specific vessel without extrapolating beyond the tested depths.

Use and supervision

Only the sensor trace end touches clean water; its connector, display, breadboard and computer remain dry. Use low-voltage USB power, disconnect before handling wet parts and dry after a short experiment. No pumps or mains wiring.

How this experiment works

Download class activity guide

Cover illustrations show component types. Functional animations explain principles and are not recorded prototype tests. Follow the supplied connection labels and pinouts.