A1.1 Water - Planning sheet
Planning sheet for topic A1.1 Water
Theme A - Unity and diversity & Level of Organisation: Level 1 - Molecules
This topic explores the properties of water? What is the structure of water molecules and how do the hydrogen bonds between water molecules give water some useful qualities which enables life? How have species adapted to live in water on Earth? There are some super illustrations with diving birds and seals. Additional HL material questions the search for extra-terrestrial life in Goldilocks zones, and poses the question whether all live really needs water.
What physical and chemical properties make water essential for life?
We say water is essential for life because all species need water for some aspect of life. This is one of the unifying characteristics of all organisms. Which properties make water so essential?This topic explores the polarity of water molecules and how hydrogen bonds form between water molecules.
Several chemical properties have been chosen to illustrate the properties of water helpful for life, for example; water is an excellent solvent of ionic salts, other polar molecules, like glucose, and small molecules such as oxygen and carbon dioxide. Molecules of water a cohesive and adhesive which explain how water moves in plants.It would take a long time to cover everything about the physical properties of water, so a few have been selected, thermal conductivity and specific heat capacity are two that everyone has experienced if they have been swimming on a hot day, or stepped out of the shower in a cold bathroom.
What are the challenges and opportunities of water as a habitat?
We can observe a huge diversity of adaptations for survival in challenging habitats in modern species. Which properties make water an easier habitat than air to live in? What are the challenges of living in water?In this topic we are introduced to two very different animals who live close to water, a diving bird the Black Throated Loon and the Leopard Seal. It's interesting to compare the ways each one solves the challenges of movement on land and in water, and how they keep warm in a cold climate but counterintuitively an environment where the water temperature changes through the seasons much less than the air temperature.
| SL & HL Understandings (2 hours) | Learning Activities |
| Atoms, molecules and bonds (2025)This quick review of the terms; element, atom, molecule and ion helps non-chemists picture molecules. With a view of H2O students can describe what a water molecule is made of and they can begin to understand... |
| Properties of Water (2025)This lesson uses a short video to introduce a simple diagram of hydrogen bonding in water. The second and third activities to help student to develop their understanding of how these hydrogen bonds affect... |
| Aquatic habitats (2025)Students identify the important properties of water as a medium for life by comparing the adaptations of the black-throated loon and the ringed seal to life on land and in water, swimming and 'walking'.... |
HL Only (1 hour) | |
| The origins of water on Earth HL (2025)Water is the medium in which enzyme reactions happen in all known living organisms. It is essential for life and many life forms use water as a habitat. We can see this in the oceans, lakes and rivers... |
This list of specific skills are mentioned in this topic. Using them during the activities is good practice for students.
- Naming species using scientific names in italics, or the full common name are both acceptable in IB assessments.
- Beware of general animal names, like "Insect" or "Fish", these are too general. Even using the terms, "Seal" or "Loon" is taking a risk, because there are several species of each. In this topic the black-throated loon (Gavia arctica) and the ringed seal (Pusa hispida) are mentioned so it would be safest to use one version of these names and to explain to students the way scientific species names are written.
This application may be used as a lens through which to view this topic.
- Global access to fresh clean water continues to pose problems.
For example:
The issue of global access to water may have been addressed in Geography by some students and they could explain the connection to biology from their experience. They could play the role of a 'visiting expert' and the class could ask them questions.
Revision resources, useful for teachers to use in class or for students to use in their individual review of the topic.
- A student friendly list of the syllabus points: A1.1 Water summary list
Revision slides
The IB-style topic test and its model answers are each on separate pages. Teachers can control access to these pages for each group of students in the Student access section of the site.
- IB-style topic test: A1.1 Water - topic test
- Model answers: A1.1 Water topic test - model answers
These questions are ideas to help link this topic to an overarching concept and / or other Biology topics
- How do the various intermolecular forces of attraction affect biological systems?
- Which biological processes only happen at or near surfaces?
- How much do the properties of water permit the transport of water by capillary action, cohesion and tension. (B3.2.7)
- Negative pressure potentials occur in xylem vessels under tension. (D2.3.10) What does this show us about the properties of water?
Approaches to teaching this topic - notes and suggestions.
There is detailed information in each of the activities linked in this planning sheet. The essence of this topic is the hydrogen bonding of water molecules which gives water some special properties for a molecule of its size.
This might be one of the first topics students see in IB Biology and it is nice that the properties of water are illustrated by such fun animal examples, even if the species are not well known by the general public. For laboratory introductions there are lots of simple experiments in the Properties of Water (2025) activities. These could be used as part of an introduction to the lab at the start of a DP Biology course.
The activity Atoms, molecules and bonds (2025) may not be needed if students have studied a basic chemistry course, but in my experience it does help a few students every year. It's important to know the difference between an ion and an atom or molecule at least.