Roots, shoots, flowers, and seeds — the green engineering that feeds the world.
Suggested pace: 3 weeks. Mastery looks like:
Plants do not move, chase, or flee, so students sometimes mistake them for simple. The opposite is true: a plant is a solar-powered chemical factory that builds itself from air, water, and soil minerals, engineers its own plumbing, and manufactures the food on which every land animal ultimately depends. Botany rewards the homeschool format especially well, because the laboratory is the yard and the experiments cost pennies.
A vascular plant runs two pipelines. Xylem carries water and dissolved minerals upward from the roots — a one-way street powered largely by transpiration, the evaporation of water from the leaves that pulls the column upward like sipping through a straw, assisted by water's cohesion. Phloem carries sugars made in the leaves to wherever the plant needs energy: growing tips, roots, fruits. A stalk of celery in colored water demonstrates xylem in an afternoon; a tree's girdled bark — which severs phloem — explains why bark damage can kill.
The leaf is built for its job. A broad, thin blade catches light; inside, the mesophyll cells are packed with chloroplasts running photosynthesis; and the underside is dotted with stomata — microscopic pores, each flanked by two guard cells that swell or relax to open and close it. Stomata admit the carbon dioxide photosynthesis needs and release the oxygen it produces, but every open pore also loses water, so the plant constantly balances feeding against drying. Peel the epidermis from a lettuce leaf under a microscope and your student can watch the guard cells themselves.
The flower is a reproductive machine. Its male organ, the stamen, holds the anther where pollen is produced; its female organ, the pistil, receives pollen at the stigma and shelters ovules in the ovary below. Pollination — by wind, bees, or birds — delivers pollen, fertilization joins the gametes, and the ovule matures into a seed while the ovary around it becomes the fruit. Seed plants come in two great groups: gymnosperms, the cone-bearers like pines whose seeds sit naked on cone scales, and angiosperms, the flowering plants whose seeds ride inside fruit. Angiosperms are the planet's dominant flora — and essentially the entire human menu.
A seed is a packed lunch and a set of instructions waiting for three signals: water, oxygen, and suitable temperature. Germination experiments are the crown of this unit because they exercise the whole scientific method — bean seeds in damp paper towels, one variable changed per jar, daily measurements in the notebook. In two weeks your student will have grown both a plant and a dataset, which is the dual-helix point of this entire curriculum: the hand and the mind, one strand.
Every correct answer climbs one rung. Climb forever. Badges at 10, 25, 50, and 100 lifetime rungs.
GENO — a robot you can actually TALK to — has studied this entire unit and is available day or night, in 32 languages, at no cost. Ask him to re-explain any idea on this page, quiz you out loud, or go deeper than the lesson goes.