DB-PZ-02 · I Sense, I Think, I Signal (BG: Усещам, мисля, давам знак)
track
PZ · The Guardians (safety systems for children) · lesson 2 of 8
level
Explorer (use · recognise · explain in words) · two levels: ages 7–10 (grades 1–4) and an extra task for ages 11–13 (grades 5–7)
duration
10–15 min on screen + 10–15 min without a screen (with other children or an adult)
school link
supports safety lessons and Human and Nature / Technology and Entrepreneurship as a cross-curricular topic (sequences, simple rules); builds on the library's electronics lessons on circuits and logic gates (DB-EL-01, DB-EL-03, DB-EL-05)
publisher
East Accelerator Foundation (Фондация „Източен Акселератор“) · host: kagami.bg
access
free · no account · no data collected · works offline
Describe the chain sensor → “brain” (control panel) → signal (sound, light, a message) → a person acts
Explain that the control panel compares what the sensor notices with a rule (a threshold) and only then gives a signal
Set a threshold in a game so that a small amount does not give a signal and a large amount does
(ages 11–13) Compare the rules AND and OR for two sensors and explain that two sensors agreeing means fewer false signals
KEY CONCEPTS
a sensor only notices; the control panel reads the sensors and decides; sirens, lights or a message tell people (Wikipedia, Security alarm)
the signal is for people, so that they can act calmly
a threshold is a rule: “give a signal from this number up”; too low gives unnecessary signals, too high gives none; game numbers 0–100 are not real units
AND: both sensors must notice; OR: one is enough; dual-technology sensors and confirmation by a second sensor reduce false alarms (Wikipedia, Security alarm)
STRUCTURE
goal → 1 Remember (3 warm-up questions: the building's senses, the school bell, what is a rule) → 2 Story (invented: two children in a school club ask how a smoke alarm “knows”, 60–90 s) → 3 Worked example (flow: sense → think → signal → a person acts; table of three chains) → 4 Try it (Predict: who decides? → Run: put two chains in order by tapping tiles → Change: threshold simulator with game numbers and a two-part mission) + extra box for ages 11–13 (two sensors, rule AND / OR, truth table) → 5 Unplugged (“The living chain”: children are sensors, the brain and the siren; the siren claps; the group makes the rules; swap roles) → 6 Make your own (invent a chain; ages 11–13: write an AND rule for two sensors) → 7 What I learned (3-question check + skill badge, no points) → 8 I have a question (form: the child writes ≤280 chars, the parent enters an e-mail and consents; double opt-in; plus "Was it useful?" / "We did the lesson" buttons — aggregate counts only)
ANSWERS
predict: b — the “brain” (control panel) decides
chain 1: sensor notices smoke → brain compares with its rule → sound and light → people go out calmly; chain 2: door magnet notices the door opened → brain: the club is closed in the evening → message to the teacher's phone → the teacher checks (it was the wind)
threshold mission: any rule above 10 and up to 80 (game numbers) — no signal at “very little” (10), signal at “a lot” (80)
ages 11–13: AND gives a signal only when both are on; OR when at least one is on
check: q1 c (sensor → brain → signal) · q2 a (compares with the rule and decides) · q3 b (for people, so they can act)
SAFETY
living chain: the siren claps or raises a hand, no screaming; walk, do not run; play in a clear space
no talk of burglars or fires; positive frame: the system notices and tells people
nothing to buy; no personal data entered or stored; the page works offline
NEXT
DB-PZ-03 · The Camera's Eye · back: DB-PZ-01 · The Building's Senses
SOURCES · LICENCE
link only, facts retold in our own words: Wikipedia, Security alarm (en.wikipedia.org/wiki/Security_alarm) — sensors; control panel reads sensor inputs and signals; alerting devices (bells, sirens, flashing lights) warn occupants; dual-technology sensors and cross-zoning (a second signal confirms) reduce false alarms; checked 2026-11-01
link only, facts retold in our own words: London Fire Brigade, Smoke alarms and heat alarms (london-fire.gov.uk) — smoke vs heat alarms; heat alarm in the kitchen; checked 2026-11-01
licence: CC BY-SA 4.0 · https://creativecommons.org/licenses/by-sa/4.0/
METADATA
path
6 · social impact
determinant
physical environment
sdg_target
4.7
who_criterion
accessibility
impact_type
prevention · education
DIGCOMP 3.0
framework
DigComp 3.0 (JRC144121, doi:10.2760/0001149)
primary
none (technology-understanding lesson: how safety systems work; no primary DigComp 3.0 competence)
secondary
3.4 Programming (sequences and simple if-then rules, unplugged precursor)
mapping
proposed 2026-11-01 by the lesson goal · confidence: medium · not a measured outcome
VERIFIED · 01.11.2026AI help: yesreviewer: awaiting teacher and psychologist
I Sense, I Think, I Signal
In lesson 1 you found the building's senses. But who understands what they notice? Today you are an engineer: you will build the chain and write the rule for when there is a signal.
⏱ 10–15 minExplorerThe Guardians · 2grades 1–7 · two levels
You will be able to tell the chain “I sense → I think → I signal” and set a rule for when the signal turns on.
For the parent: a one-page guide — questions for dinner and the game “The Living Chain”.
progress0%
01Remember
Think about each question, then open the answer.
What are the building's senses?
The camera (eye), the intercom (ear), the smoke alarm (nose), the heat alarm (skin) and the magnet on the door (touch). Do you remember them from lesson 1?
How do you know it is break time?
The bell rings. Someone made a rule: “When 45 minutes have passed — ring.” The bell is a signal for everyone.
What is a rule?
Something we agreed on beforehand. For example: “When the traffic light is green — we go.”
02Story
This story is made up.
In the technology club, Nia looks at the white circle on the ceiling.
“How does the smoke alarm know when to sound?” she asks. “Does it think?”
The teacher smiles. “The sensor only senses. A big building also has a “brain” — a control panel. It gets the signal from the sensor and thinks: “Is this more than the rule?””
“And if it is more?” Bobby asks.
“Then it gives a signal: it turns on sound and light. It can also send a message to a person.”
“So the signal is for people!” says Nia. “So they know what to do.”
“Exactly. Let's build a chain like that. You will be the sensor, and Bobby will be the brain.”
03Worked example
Every system like this works as a chain of four steps:
👃 I SENSEsensor
🧠 I THINKcontrol panel
🔔 I SIGNALsound · light · message
🧑 A PERSONunderstands and acts
The sensor senses
The brain thinks (rule)
The signal
Smoke sensor — smoke in the air
“Is it more than the rule?”
sound and a flashing light
Magnet on the door — the door opened
“Is the club closed now?”
a message to the teacher's phone
Motion sensor — someone walked by
“Is it dark in the hallway?”
the light turns on
The “brain” is called a control panel. It reads what the sensors say and compares it with a rule. The number from which there is a signal is called a threshold. The signal is for people — so they understand and do something calmly.
04Try it now
1 · Predict
The sensor noticed something. Who decides whether there is a signal? Choose before you check.
2 · Run: put the chain in order
Tap the tiles one by one — from the first step to the last.
3 · Change: when should there be a signal?
You are the engineer. The numbers here are game numbers — from 0 to 100. They are not real measurements.
Mission:
For older children · ages 11–13
Now the brain listens to two sensors. Turn each one on and off and choose the rule.
🚶 Motion
🧲 Door
AND
OR
no
no
no signal
no signal
no
yes
no signal
🔔 signal
yes
no
no signal
🔔 signal
yes
yes
🔔 signal
🔔 signal
Think: a butterfly can fly past the motion sensor. But it cannot open the door. So when two sensors must agree (rule AND), there are fewer unnecessary signals. With OR the brain reacts faster, but also more often without need. Engineers choose according to the place.
05No screen: the living chain
You need: at least 4 children (or a child and adults), a few slips of paper and a clear space. Everyone chooses a role — you can also just watch the first round.
Roles. Two or three are sensors. One is the brain. One is the siren. The others are the people in the building.
The rule. The group decides together and writes it down: for example, “The brain gives a signal when at least one sensor raises a hand.”
Play. The leader shows a slip to the sensors: 🌫️ “smoke” or ☀️ “nothing”. A sensor who sees “smoke” raises a hand. The brain watches the sensors and checks the rule. If the rule is met, the brain touches the siren on the shoulder.
The signal. The siren claps twice and raises a hand — no shouting. The people stand up and calmly walk to the door.
Swap. Everyone swaps roles. Try another rule too. Which rule did you like, and why?
For older children · ages 11–13Change the rule to AND: “There is a signal only if both sensors raise a hand.” Sometimes the leader shows “smoke” to only one of them. Talk about it: when does the AND rule prevent unnecessary signals? When is OR better?
✋
Calm and quiet
The siren claps, it does not shout. Everyone walks, nobody runs. Play in a clear space, away from stairs and corners.
06Make your own
Invent your own chain. Draw it as four boxes with arrows.
I sense: which sensor? For example, a moisture sensor in a flower pot.
I think: what is the rule? For example, “If the moisture is below 30 (a game number)…”
I signal: what kind? A little light, a sound or a note.
The person: who understands and what do they do? For example, “I water the plant.”
For older children · ages 11–13Write a rule with two sensors and the word AND. For example: “If it is dark AND someone walks along the hallway — turn on the light.” Why is AND better than OR here? Draw a table with the four cases, like the one in the game.
07What I learned
The chain is: the sensor senses → the brain (control panel) thinks → a signal — sound, light or a message.
The brain compares with a rule. The number from which there is a signal is the threshold.
The signal is for people — so they understand and act calmly.
When you hear your name in a noisy room, what does your head do?
Check yourself
1. How is the chain ordered?
2. What does the brain (control panel) do?
3. Who is the signal for?
🧠
Skill badge: “I build the chain” It is yours when you can tell someone “I sense → I think → I signal” and give an example of a rule. No points and no ranking — only a skill.
08I have a question
Do you still have a question? Write it here. It goes to your parent, not to strangers. Your parent confirms their e-mail first.
The form is loading… If it does not appear, write your question on paper and show it to a parent or teacher.
·Sources
Title: I Sense, I Think, I Signal (DB-PZ-02) · Author: Children's Library, East Accelerator Foundation · Source: original content and original game code, 2026 · Rights: CC BY-SA 4.0.
Wikipedia — “Security alarm”: the parts of an alarm system — sensors; a control panel that reads the sensors and decides; bells, sirens and flashing lights that warn people. Combining two kinds of detection, or waiting for a second sensor to confirm, reduces false alarms. Checked 01.11.2026.
London Fire Brigade — “Smoke alarms and heat alarms”: smoke alarms detect smoke, heat alarms detect rapid increases in heat; a heat alarm goes in the kitchen instead of a smoke alarm. Checked 01.11.2026.
Licence:CC BY-SA 4.0 · Children's Library, East Accelerator Foundation, 2026. You may share and adapt this lesson if you credit the author and keep the same licence. Learning is free forever.
