Just closely examine the leaf of a rose plant or a peepal tree. A waxy layer protects the top surface of the leaf. This covering protects the leaf and also prevents water loss. The flat part of the leaf is called the leaf blade. The tip of a leaf is called the leaf apex. The colour of the upper and lower sides of a leaf blade differs slightly. The top is smooth and dark, while the bottom is rough and light.

 A tiny tube passes through the centre of every leaf. This is known as the main vein or midrib. Some other small tubes that are attached to the midrib are called side veins.  Water, nutrients, and food are transported along these veins to all sections of the leaf and the rest of the plant. They also give the leaf blade strength and aid in maintaining the shape of the leaf. There are many tiny pores found on the underside of a leaf called stomata (singular: stoma). We can't see these pores with our naked eyes since they're so small.

Through the stomata, carbon dioxide enters the leaf, and oxygen and water vapour are released during photosynthesis. The stomata allow oxygen to enter and carbon dioxide to exit during respiration.

NGSS

LS1.A: 

LS1.B: 

LS1.D:

LS3.A: 

LS3.B: 

K.ETS1.A (1-LS1-1); 3.LS2.D (1-LS1-2); 3.LS3.A (1-LS3-1); 3.LS3.B (1-LS3-1); 4.LS1.A (1-LS1-1); 4.LS1.D (1-LS1-1); 4.ETS1.A (1-LS1-1)

Common Core State Standards Connections:

Let's do an activity that demonstrates how carbon dioxide is required for plants to produce food.

Take a handful of leaves from a nearby plant. Pick a leaf that is green. Cover both sides of the leaves with any type of body lotion or moisturiser you have on hand. Keep that leaf out in the open for at least two days. Check for starch in the leaf. Also, look for starch in another leaf from the same plant. Which leaf has a lot of starch on it? Why? 

When iodine is added to a leaf that has been covered with body lotion or moisturiser, it does not become blue-black. This occurs because the stomata pore on the leaf is blocked by body lotion or moisturiser. As a result, carbon dioxide is unable to enter the leaf. This brings the photosynthetic process to a halt.

NGSS

 5-LS1-1

LS1.C: 

Common Core State Standards Connections

• RI.5.1 - 

• RI.5.9 - 

• W.5.1 -)

Mathematics

• 5.MD.A.1 - 

• MP.2 - 

• MP.4 - 

• MP.5 -