Stem-La Tuition Botswana

‎C2 – Atoms, elements and compounds (IGCSE Chemistry)
‎
‎1. Atom: the basic building block of matter; consists of protons, neutrons & electrons.
‎
‎2. Element: a pure substance made of only one type of atom (e.g H, O, Fe) Defined by its atomic number (number of protons).
‎
‎3. Compound: a substance formed when two or more different elements are chemically bonded (e.g, H₂O, NaCl)
‎
‎
‎4. Atomic structure
‎- Protons (+ charge) in the nucleus.
‎- Neutrons (neutral) in the nucleus.
‎- Electrons(– charge) in shells/orbitals around the nucleus.
‎
‎- Atomic number (Z): number of protons; identifies the element.
‎- Mass number (A): total protons + neutrons.
‎- Isotopes: atoms of the same element with different neutron numbers (same Z, different A).
‎- Electronic configuration: arrangement of electrons in shells (2,8,8… for the first three shells). Determines chemical reactivity.
‎
‎5. Chemical bonding
‎
‎- Ionic: transfer of electrons and ions that attract (metal + non‑metal).
‎- Covalent: sharing of electron pairs (non‑metal + non‑metal).
‎
‎6. Formulae
‎
‎- Empirical: simplest whole‑number ratio of atoms in a compound.
‎- Molecular: actual number of atoms in a molecule.
‎
‎7. Mixtures vs compounds
‎
‎Mixtures can be separated by physical means whilst compounds require chemical reactions to separate.

P1 – Forces (IGCSE Physics)
‎
‎1. Types of forces
‎- Contact forces: friction, tension, normal reaction, air resistance.
‎- Non‑contact forces: gravitational, electrostatic, magnetic.
‎
‎2. Force effects
‎
‎- A force can change an object's speed, direction, or shape.
‎- Forces are vectors– they have magnitude and direction.
‎
‎3. Newton’s laws of motion
‎
‎- 1st law (inertia): An object stays at rest or in uniform motion unless a resultant force acts.
‎- 2nd law: F = ma (resultant force = mass × acceleration).
‎- 3rd law: For every action there is an equal & opposite reaction.
‎
‎4. Weight & mass
‎
‎- Weight = gravitational force on an object: W = mg (g approx 9.81, sometimes, rounded off to 10)
‎- Mass is the amount of matter (scalar).
‎
‎5. Resultant force
‎
‎- Sum of all forces acting on an object determines its acceleration.
‎- For balanced forces, resultant = 0 → no acceleration (equilibrium).
‎
‎6. Friction
‎
‎- Acts opposite to motion.
‎- Static friction (prevents motion) ≥ kinetic friction (opposes motion).
‎
‎7. Hooke’s law (elastic forces)
‎
‎- F = kx, where k is the spring constant, x is extension.
‎- Applies to elastic deformation within the limit of proportionality.
‎
‎8. Moments (turning effect of forces)
‎
‎- Moment = force × perpendicular distance from pivot.
‎- Principle of moments: for equilibrium, clockwise moments = anticlockwise moments.
‎
‎Key equations
‎
‎ F = ma
‎ W = mg
‎ F = kx
‎

B2 – Cells (IGCSE Biology)
‎
‎1.Cell basics
‎
‎-Basic unit of life.
‎-All living organisms are made of one(unicellular)or more cells(multi-cellular)
‎
‎2.Cell structure (typical animal & plant cells)
‎
‎-Cell membrane: thin, flexible barrier controlling what enters/exits.
‎-Cytoplasm: jelly‑like substance where chemical reactions happen.
‎-Nucleus: control centre containing DNA (genetic material)
‎-Mitochondria: “powerhouse” – produce energy (ATP) via respiration.
‎-Ribosomes: site of protein synthesis.
‎
‎- Plant‑specific: cell wall (rigid cellulose), chloroplasts (photosynthesis), large vacuole (food storage)
‎
‎3.Cell functions:
‎
‎-Cell division: mitosis (growth/repair) & meiosis (gametes).
‎-Transport: diffusion, osmosis (water movement), active transport (energy‑using)
‎
‎4.Specialised cells:
‎
‎-Nerve cell (neuron): transmits electrical impulses.
‎-Muscle cell: contracts for movement.
‎-Root hair cell: increases surface area for water absorption.
‎
‎5. Cell organisation:
‎
‎-Cells then tissues then organs then organ systems, making an organism(multi-cellular)
‎
‎*tips*
‎
‎- Draw and label animal & plant cell diagrams.
‎- Describe functions of organelles in energy & protein processes.
‎

CALL FOR ENTRIES FOR THE 2026 SADC TERTIARY INSTITUTION ESSAY COMPETITION

The SADC Tertiary Institution Essay Competition is open to all active tertiary institution-going students in the SADC Member States. This competition aims to raise awareness among the students to research and articulate issues to support the process of SADC regional cooperation, integration and socio-economic development.

The topic for the 2026 SADC Tertiary Institution Essay Competition is; “Compare and contrast the challenges faced by the SADC founders in the 20th century against the current challenges. Which lesson(s) from the SADC Founders would you advise or adapt to address today’s regional dilemma(s)?”

DEADLINE: Submit to Ministry of Higher Education, Botswana by 31st January 2026. Postal Mail should be addressed to:

Permanent Secretary
Ministry of Higher Education
Private Bag 00517
Gaborone

OR Hand Delivered to Records Management Unit, Floor 8, Office 28.

OR Email [email protected]
For more information visit the links below:

Brochurehttps://www.sadc.int/sites/default/files/2025-11/English%20Brochure%20-%20TERTIARY%20INSTUTION%20COMPETITION%202026.pdf

Entry Formhttps://www.sadc.int/sites/default/files/2025-11/English%20Entry%20Form%20-%20SADC%20Tertiary%20Institution%20Essay.pdf

Marking guidelineshttps://www.sadc.int/sites/default/files/2025-11/English%20-%20Marking%20Guidelines%20-%20Tertiary%20Schools%20Essay%20Competition%20topic%202026.pdf

VACANCY

CALL FOR REGISTRATION OF UNEMPLOYED GRADUATES FOR TEMPORARY APPOINTMENT AS RECEPTION TEACHERS/TEACHER AIDES TENABLE IN CENTRAL REGION SCHOOLS

C1 – States of Matter [IGCSE CHEMISTRY]
‎
‎Three classic states: solid, liquid, gas.
‎
‎Particle arrangement:
‎-Solid: particles tightly packed, fixed positions, vibrate.
‎-Liquid: particles close but can move past each other, no fixed shape.
‎-Gas: particles far apart, move freely.
‎
‎Properties:
‎Solids: fixed shape & volume.
‎Liquids: fixed volume, takes shape of container.
‎Gases: no fixed shape or volume, compressible.
‎
‎Changes of state:
‎-Melting: solid to liquid (heat absorbed).
‎-Freezing: liquid to solid (heat released).
‎-Boiling/Evaporation: liquid to gas (heat absorbed).
‎-Condensation: gas to liquid (heat released).
‎-Sublimation: solid to gas (e.g., dry ice).
‎
‎
‎Energy in phase changes
‎-Heat energy breaks or forms intermolecular forces; temperature stays constant during change (latent heat).
‎
‎Kinetic theory
‎-Particles in all states are in constant motion
‎
‎Diffusion
‎-Gas particles spread out to fill space; faster in gases than liquids.
‎
‎Key exam tips:
‎
‎- Define each state with particle diagrams.
‎- Explain changes of state using energy and particle behavior.
‎ Compare properties (density, compressibility) of solids, liquids, gases

P1: (1) Motion [IGCSE PHYSICS]
‎
‎1. Distance vs Displacement
‎
‎Distance: Total path length traveled.
‎Displacement: Shortest path from start to end point.
‎
‎2. Speed vs Velocity
‎
‎Speed: How fast an object moves (scalar).
‎Velocity: Speed with direction (vector).
‎
‎3. Acceleration
‎Change in velocity over time.
‎
‎ v = u + at
‎
‎ Equation Breakdown: v = u + at
‎
‎v: Final velocity (m/s)
‎u: Initial velocity (m/s)
‎a: Acceleration (m/s²)
‎t: Time (s)
‎
‎This equation describes how velocity changes over time when an object accelerates.
‎
‎Example: A car accelerates from 10 m/s to 30 m/s in 4 s. Find acceleration.
‎u = 10 m/s
‎v = 30 m/s
‎t = 4 s
‎
‎And the answer?

B1: Characteristics of Living Organisms [IGCSE BIOLOGY]
‎
‎Definition
‎
‎Living things (organisms) share 7 basic characteristics (MRS GREN).
‎Used to distinguish life from non‑life (rocks, machines).
‎
‎The 7 Characteristics (MRS GREN)
‎
‎1. M– Movement
‎All living things can move parts of themselves (e.g, muscle contraction in animals, cytoplasmic stream in plants)
‎
‎2. R– Respiration
‎Chemical reactions that release energy from food (glucose)
‎Can be aerobic (in the presence of O₂) or anaerobic (without O₂)
‎
‎3. S– Sensitivity (Response to stimuli)
‎Detect changes in environment & react (e.g., plant shoots bend toward light – phototropism)
‎
‎4. G– Growth
‎Increase in size & complexity by making new cells.
‎
‎5. R– Reproduction
‎Produce offspring – asexual (single parent, clones) or sexual (two parents, genetic mix)
‎
‎6. E– Excretion
‎Remove waste products (e.g., CO₂, urea) that result from metabolism.
‎
‎7. N– Nutrition
‎Obtain & process food for energy & building blocks.
‎Autotrophs(plants – photosynthesis). Heterotrophs (animals – ingest [eat organic material] )
‎
‎Mnemonic to Remember
‎
‎M*y R*ed S*ocks G*ive R*eally E*asy N*otes 🤣 🧠
‎

Chemistry - Matter

Everything around us is made up of matter, from the air we breathe, water we drink or a piece of clothing worn and those are the three states in which matter exists, as a gas, liquid or solid, respectively. In fact, the human body consists of all three states of matter, i will leave that for you to identify.

A simpler example of understanding matter and how it can change its state is through studying water vapour, which is a gas, water at room temperature, which is a liquid and ice, which at that state is a solid.

Gas - Liquid
Water vapour loses heat energy, the particles cool down. With the loss of heat energy, kinetic(movement) energy is also reduced, the particles are less scattered, they accumulate and slide past each other to form a liquid. This process is called condensation.

Liquid - Solid
Water, which is a liquid can also lose heat energy, the particles further cool down even more heat is lost hence kinetic energy is also greatly reduced, the particles are now closely packed, forming a lattice where movement is only in the form of vibrations as the particles hit against each other and that is how a solid called ice is formed, through freezing.

Solid - Liquid
When ice is exposed to any temperature increase above 0 degrees celsius, the particles gain heat energy, they begin to vibrate and push further against each other , this is how water is formed from ice and it is called melting.

Liquid - Gas
If you apply heat to a liquid such as water, particles gain heat energy which converts to kinetic energy, they move further apart and form a gas called steam, and since it is less dense than air it rises, only to cool at a later time. The rise of this less dense form of matter is called evaporation.

Know what sublimation is? Comment below and share the knowledge with fellow scholars