The four factors
Four things have to be present, and if any one of them is missing nothing is made. The next four skills of this chapter each remove one and show what happens.
Chlorophyll
The green pigment held inside the chloroplasts. Without it, no amount of sunlight produces food.
Sunlight
The energy source. It is the energy in the light that is used, not the light itself.
Water
H2O, taken up from the soil by the roots.
Carbon dioxide
CO2, taken from the atmosphere through the leaf.
Two of the four are not the same kind of thing
Raw materials — water and carbon dioxide
These are consumed. Their atoms end up inside the glucose the plant makes. Take them away and there is nothing to build from.
Conditions — sunlight and chlorophyll
These are not consumed. Sunlight drives the process and chlorophyll captures it, and neither ends up inside the glucose. Grade 10 made this point about the two written above and below the arrow.
Which is why only two of them appear in the equation
Look at the balanced equation and you will find carbon dioxide and water on the left and glucose and oxygen on the right — but no sunlight and no chlorophyll anywhere among the reactants. They are written on the arrow precisely because they are needed and are not used up. The distinction is not a technicality; it is what the equation is telling you.