Educational worksheet for students to learn about energy sources using a dichotomous key.

Explanation:
We are given a dichotomous key (a step-by-step classification tool) to match each energy source image (A–J) with the correct label based on its characteristics.

Let’s go through each image and use the key to identify it.

First, list the images and what they show (based on standard interpretation of such diagrams):

- A: Cloud with rain → likely hydropower (moving water from rain/precipitation)
- B: Sun → solar
- C: Earth/globe with heat lines → possibly geothermal (energy from inside Earth)
- D: Tree → biomass (plant material that can be burned)
- E: Wind turbine → wind
- F: Coal in a cart → coal
- G: Flame → could be biomass, fossil fuel, or natural gas — but we’ll narrow it down
- H: Oil derrick/tower → petroleum
- I: Uranium symbol (U with 235) → uranium (nuclear fuel)
- J: Propane tank → propane (a type of natural gas, shipped in tanks)

Now use the key step by step.

The key is structured as paired choices (1a vs 1b, etc.). We start at 1 and follow the path.

But note: the bottom grid shows some clues already filled in:
> 1a – 2b –
> 3b – 4b –
> 5a

That’s a path:
1a → 2b → 3b → 4b → 5a

Let’s trace that path:

1a. Renewable → go to 2
2b. Is not burned → go to 3
3b. Energy in/on the earth → go to 4
4b. On the earth’s surface → go to 5
5a. Moving water → Hydropower

So this path leads to Hydropower, which matches image A (rain/cloud → water cycle → hydropower). So A = Hydropower.

Now let’s match all others using the key.

We’ll go image by image and find which path fits.

Image B: Sun
- Renewable? Yes → 1a
- Can be burned? No (sunlight isn’t burned) → 2b
- Energy from space? Yes → 3a → go to 2? Wait, key says 3a → go to 2 — but we’re already at 2. Let’s re-read key:

Key:
1a Renewable → go to 2
1b Nonrenewable → go to 6

2a Can be burned → Biomass
2b Is not burned → go to 3

3a Energy from space → Solar
3b Energy in/on the earth → go to 4

So for Sun:
1a (renewable) → 2
2b (not burned) → 3
3a (energy from space) → Solar ✔
So B = Solar

Image C: Globe with heat lines (geothermal)
Renewable? Geothermal is considered renewable → 1a
Is not burned? Yes (heat from Earth, not combustion) → 2b
Energy in/on earth? Yes → 3b → go to 4
4a Inside the earth → Geothermal
4b On earth’s surface → ?
So C = Geothermal → matches 4a

Image D: Tree
Renewable? Yes → 1a
Can be burned? Yes → 2a → Biomass ✔
So D = Biomass

Image E: Wind turbine
Renewable? Yes → 1a
Is not burned? Yes → 2b
Energy from space? No → 3b
Energy in/on earth? Yes → 4
On earth’s surface? Yes → 4b → go to 5
5a Moving water → no
5b Moving air → Wind ✔
So E = Wind

Image F: Coal
Nonrenewable → 1b → go to 6
6a Fossil fuel → Coal ✔
So F = Coal

Image G: Flame
This is tricky — flame suggests combustion. Could be biomass, fossil fuel, or gas.

But D is already biomass (tree), F is coal, H is petroleum, J is propane.

Flame alone could represent *any* combustible fuel, but in this context, likely biomass is already taken (D), so maybe this is *natural gas* or *propane*? But J is propane tank.

Wait — look at key option 7a: “A gas” → go to 8
7b: “A solid or liquid” → go to 9

If G is a flame from burning gas (like methane), then:
1b (nonrenewable? Natural gas is nonrenewable) → 6
6b: Energy-rich mineral → Uranium? No, natural gas isn’t a mineral.
Actually, natural gas is a fossil fuel, so 6a: Fossil fuel → go to 7
7a: A gas → go to 8
8a: Moved by pipeline → Natural Gas
8b: Shipped in tanks → Propane

So if G is generic flame, maybe it's meant to be biomass — but D is tree = biomass.

Hold on — maybe G is *biomass* and D is something else? No, tree is classic biomass.

Let’s instead match the remaining letters using the key fully.

List all key endpoints:
- Biomass → 2a
- Solar → 3a
- Geothermal → 4a
- Hydropower → 5a
- Wind → 5b
- Coal → 6a
- Uranium → 6b
- Natural Gas → 8a
- Propane → 8b
- Petroleum → 9b
(9a is “Mined from earth” → Coal, but coal is already 6a — maybe redundancy)

Now assign images:

A: rain → hydropower → 5a ✔
B: sun → solar → 3a ✔
C: Earth heat → geothermal → 4a ✔
D: tree → biomass → 2a ✔
E: wind turbine → wind → 5b ✔
F: coal cart → coal → 6a ✔
H: oil rig → petroleum → 9b ✔
I: U-235 → uranium → 6b ✔
J: propane tank → propane → 8b ✔

That leaves G (flame) unassigned. What’s left? Natural Gas (8a). Natural gas is a gas, moved by pipeline. A flame could represent burning natural gas (e.g., stove flame). So G = Natural Gas → 8a.

Check:
G → nonrenewable (yes) → 1b → 6a (fossil fuel) → 7a (a gas) → 8a (moved by pipeline) = Natural Gas ✔

All 10 matched:

A – Hydropower
B – Solar
C – Geothermal
D – Biomass
E – Wind
F – Coal
G – Natural Gas
H – Petroleum
I – Uranium
J – Propane

Now verify with the partial path given:
“1a – 2b – 3b – 4b – 5a” → A (hydropower) — correct.

So final matching:

A → 5a (Hydropower)
B → 3a (Solar)
C → 4a (Geothermal)
D → 2a (Biomass)
E → 5b (Wind)
F → 6a (Coal)
G → 8a (Natural Gas)
H → 9b (Petroleum)
I → 6b (Uranium)
J → 8b (Propane)

The question likely asks: *Fill in each square* — meaning for each image letter (A–J), write the correct term or code.

Since the worksheet has a grid with images A–J, and the instruction says “fill in each square, using hydropower as an example”, the expected answer is the name of the energy source for each image.

Thus:

A: Hydropower
B: Solar
C: Geothermal
D: Biomass
E: Wind
F: Coal
G: Natural Gas
H: Petroleum
I: Uranium
J: Propane

Final Answer:
A: Hydropower, B: Solar, C: Geothermal, D: Biomass, E: Wind, F: Coal, G: Natural Gas, H: Petroleum, I: Uranium, J: Propane