Look for: Air, water, hydroponic plant food, and light…

3.A Construct an explanation by applying scientific reasoning to show why data found in images and charts show patterns that parts of inputs could be the source of food molecules in a plant.

• Air, water, hydroponic plant food, and light do not contain any whole food molecules.
• The air composition chart shows that air contains carbon dioxide (carbon and oxygen) and oxygen molecules that are parts of each food molecule’s structure.
• Water has hydrogen and oxygen atoms.
• Hydroponic plant food has nitrogen and sulfur, which are atoms found in proteins and amino acids.
• All the parts of food molecules can be accounted for if you combine parts of the air, water, and hydroponic plant food.
• We have confirmed in Lesson 2 investigations that water and hydroponic plant food go into the plant but have yet to confirm that air enters the plant.

If your students struggle with identifying why the question needs to be revised to include parts instead of just (whole) food molecules, have your students revisit the air composition chart and Food Molecule Cards. Cue students to look for similarities in the atoms present in air and food molecules. You can also cue them to look back at their Progress Trackers from Lesson 2 to confirm that soil is not needed for plants to grow and that hydroponic plant food and water do go into the plant as it gets bigger. Then they can revisit the nutrition labels for plant food and water to see what parts of food molecules are found in the ingredients.