Lesson guide · Lesson 3 · Grades 3–8 · 7 min

Roots: drinking, eating, breathing

Roots drink water, take in plant food, and breathe air, all at the same time.

Open the lessonPrintable worksheet

Students will

  • Name three parts of a root: root hairs, root tip, and main root.
  • Explain that roots take in water and dissolved nutrients through root hairs.
  • Explain that roots need air, and why soggy soil can harm a plant.

New words

root-hairs
Tiny threads near the end of a root that soak up water and plant food.

Talk about it

Why might a plant in a pot with no drain holes start to droop, even with lots of water?

Check questions and answers

  1. Where on a root do you find most root hairs?

    • A little way back from the tip (answer) Right. They grow just behind the growing tip.
    • Right on the very tip Not quite. The very tip has no root hairs. Look a little higher up.
    • On the leaves Not quite. Root hairs grow on roots, down where the water is.

  2. Why do roots need air?

    • To get energy for their work (answer) Right. Roots use air to get energy from sugar.
    • To dry off Not quite. Roots like water. Think about the work roots do.
    • To make sugar Not quite. Leaves make sugar. Roots use air to get energy.

  3. A pot sits in a tray of water for weeks. The plant droops. Why?

    • Water filled every gap, so roots couldn't breathe (answer) Right. Soaked soil has no room left for air.
    • It needed even more water Not quite. It has lots of water. What is missing from the gaps?
    • The roots grew too long Not quite. Think about what fills the gaps in soaked soil.

Sources

  • VanDerZanden, A. M. Vegetative Plant Parts. EM 9904. Oregon State University Extension Service, 2008 (reviewed 2024).
  • Moore, K. A., and L. K. Bradley, eds. "3. Botany." North Carolina Extension Gardener Handbook, 2nd ed. NC State Extension, AG-831, 2022.
  • Cogger, C. A Home Gardener's Guide to Soils and Fertilizers. EM063E. Washington State University Extension, 2014 (revised 2020).
  • Jones, C., and K. Olson-Rutz. Plant Nutrition and Soil Fertility. Nutrient Management Module No. 2, 4449-2. Montana State University Extension, 2016.
  • Pan, B. Nutrient Movement Towards and Into Plant Roots. Soils 441, Unit 1, Lesson 4. Washington State University.
  • Wilted plants with lots of water. Southwest Yard & Garden. New Mexico State University, College of Agricultural, Consumer and Environmental Sciences, 2006.
  • Trinklein, D. Wet Weather Woes. Integrated Pest Management, University of Missouri, 2015.
  • Kaiser, C., and M. Ernst. Hydroponic Lettuce. CCD-CP-63. Center for Crop Diversification, University of Kentucky College of Agriculture, Food and Environment, 2016.
  • Nelson, M., G. Langellotto, and L. Nackley. Hydro Hints: Deep Water Culture. EM 9455. Oregon State University Extension Service, 2025.
  • Lin, C., T. Zhu, L. L. Peralta Ogorek, Y. Wang, M. Sauter, and O. Pedersen. The Pyramiding of Three Key Root Traits Aid Breeding of Flood-Tolerant Rice. Plants 11(15): 2033, 2022.