4 mistakes learners make with the atmosphere, each one named and explained.
Air is mostly nitrogen, about a fifth oxygen, and a very small amount of everything else.
Hydrogen or another trace gas is given as a main component of the atmosphere.
Hydrogen is the most common element in the universe, which makes it a plausible guess.
Question. Which gas is about 78 per cent of the air
A common answer. hydrogen
The answer. nitrogen
Why. Free hydrogen is so light that it escapes the atmosphere almost entirely.
The composition of air is a local fact about this planet, not a general one.
Nitrogen, oxygen or helium is named as the greenhouse gas released by burning fossil fuels.
All are gases, all are in the air, and the link to burning is not made explicit.
Question. Which gas from burning fossil fuels adds to the greenhouse effect
A common answer. nitrogen
The answer. carbon dioxide
Why. Fossil fuels are made of carbon, so burning them releases carbon dioxide.
Start from what the fuel is made of. Carbon in means carbon dioxide out.
Carbon dioxide is chosen as a major component of the atmosphere.
It is discussed constantly because of climate change, so it feels like a large quantity.
Question. Which gas is about 78 per cent of the air
A common answer. carbon dioxide
The answer. nitrogen
Why. Carbon dioxide is about 0.04 per cent, which is why it is measured in parts per million.
How much something is talked about says nothing about how much of it there is.
Oxygen is given as the gas making up 78 per cent of the air, or as half or more of it.
Oxygen is the gas that matters to you, and the one every lesson about air mentions.
Question. Which gas is about 78 per cent of the air
A common answer. oxygen
The answer. nitrogen
Why. Oxygen is about a fifth; nitrogen is roughly four fifths.
Important is not the same as abundant. Oxygen matters most and is not the most.
WAJD spots these patterns in your child's answers and names the one behind their wrong answers, instead of just marking them wrong.