This document is a worksheet created by Cambridge Assessment International Education for Cambridge Lower Secondary Science Stage 9. Cambridge Lower Secondary Science includes learning objectives on models and representations because they are central to students' understanding of science.
Suggested activities
Creating physical models is used here to stimulate discussion with students about the strengths and limitations of the dot-and-cross pattern. If you remove one of the electron counters, how many protons and electrons are there now?
Plant biology
Simple atomic models can be used to represent the reactants and products of the summary word equation for photosynthesis. Online animations can be used to show the reactants and products of the summary word equation for photosynthesis.
Suggested activities
Give students a diagram of the carbon cycle and give them a few minutes to study it in pairs. Ask students to sort the statements by matching them with one of the key processes in the carbon cycle.
Chemical structures and properties
As part of this unit, learners will be introduced to, and use, the Bohr model of the atom. There are other forms of the Periodic Table that learners can explore and discuss the strengths and limitations of each.
Suggested activities
Ask students to suggest the relationship between the structure of atoms as we go down group 1 and. Sources: mass balances, water containers, list of objects and their densities, picture of the Dead Sea.
Sound and energy
A toy "slinky" (compressed coil spring) can be used to model the travel of longitudinal waves (eg sound waves). Kinetic theory can be used to model temperature, since temperature is a measure of the kinetic energy that particles in a material or object have. You can show the difference between heat and temperature by adding more balls to the plate without changing the motion of the plate.
The three different methods of heat transfer can be modeled using three bean bags given to learners. The beanbags can be returned to you by passing (conduction), carrying (convection) or throwing (radiation).
Suggested activities
How could you model an increase in the loudness of the sound wave that is produced. How is the amplitude of the wave measured. from a peak or trough to the x-axis). Students observe and discuss how the interaction of the waves is different from the first demonstration.
Discuss with the students that the higher the initial temperature of the beaker, the faster the temperature drops. Why does the egg dry quickly when removed from the water? water evaporates from the surface of the shell).
Human biology
Human biology (12 hours)
Some learners may need guidance on what the term 'excretion' means in terms of the human renal system; 'excretion' can sometimes be confused with 'estie'. The idea that 'dirty' blood is filtered to make the blood 'clean' may be held by some learners. Pedigree diagrams and Punnet squares can be used to show the inheritance of X and Y chromosomes.
XX and XY and their role in humans can be confused (especially if learners find out about sex determination in other species such as birds). Videos that discuss how the health of a mother affects fetal development are useful for depicting real-world examples that learners can relate to, but such videos should be previewed to ensure they are appropriate for learners.
Suggested activities
Alternatively, learners can use printed templates of DNA and color suitable lengths of the completed models to represent one, two or three genes (depending on the template used). Resources: An animation of the relationships between DNA, genes and chromosomes; DNA model kits, a video of the discovery of the structure of DNA and the functions of genes, string. Explain that the fusion of the two gametes created a fertilized egg with a new combination of chromosomes (and genes and DNA) from those of the parents who produced the gametes.
Resources: An animation of gamete fusion, a set of diagrams of the stages of gamete fusion 9Bp.02 Describe. Ask the pairs to record the sex chromosomes shown, the sex chromosomes of the 'fertilised egg'.
Electricity
The more circuit components (learners gently holding the string) added to the string, the slower the current will move (ie, the more resistance, the lower the current). Good use of models (eg the queue model) is invaluable for supporting concept development and addressing. This misconception can be investigated by looking at what a cell (a battery) is and what it is made of.
Pupils can be added to represent more cells in a circuit; they increase the amount of traction (energy) transferred to the rope loop. Pupils can be added to represent light bulbs in the circuit: they increase the resistance to the movement of the loop making the loop move more slowly, representing a lower current.
Suggested activities
In a circuit with more bulbs, there is more resistance and therefore less current. What effect does the new component have on the current in the circuit. can change current). What effect does the new component have on the bulb in the circuit. can change brightness).
Discuss how the sum of the voltages across the components in a series circuit equals the voltage across the cells. What would happen to the current through each lamp if a fourth lamp were added in series. the current would reduce because adding a fourth lamp would increase the total resistance of the circuit).
Chemical reactions
Learners may find it difficult to understand the abstract concepts of conservation of mass and energy. For example, learners may think that mass is not conserved in chemical reactions involving colorless gases (reactants or products). 9Cc.02 Identify examples of displacement reactions and predict products (limited to reactions involving calcium, magnesium, zinc, iron, copper, gold and silver salts).
Learners can use or draw diagrams of the particle model of solids, liquids and gases when describing the different purification techniques. Learners can also use the particle model, word equations and symbol equations to demonstrate their understanding of the reaction of metals with acids and metal carbonates with acids.
Suggested activities
Discuss with learners some examples of the conservation of energy in a closed system (eg heat that is distributed from a hot object to the surrounding environment). Give each learner a copy of the reactivity series of metals (limited to calcium, magnesium, zinc, iron, copper, gold and silver). Learners discuss their findings and draw a conclusion for the effect of the concentration of acid on the rate of the reaction.
They then discuss their findings and draw a conclusion about the effect that the temperature of acid has on the rate of reaction. Note: Heating acid can be dangerous and students should not heat it above 60oC. They then discuss their findings and come to a conclusion about the effect of the magnesium surface area on the reaction rate.
Species and their environments
Animations and videos can be used to show the variations within a range of species and how these are related to the genetic differences between them. Online simulations can be used to demonstrate past and potential impacts of climate change. Computer modeling can be used to predict the future impacts of climate change (eg sea level changes).
Students may get confused between global climate change (ie warming) and regional climate change, which can be warming or cooling. Explain that some asteroids are as small as pebbles, while others can be hundreds of kilometers in diameter.
Suggested activities
Some of the traits that resulted from the genetic changes helped those animals survive and reproduce. Give pairs of students a series of pictures that illustrate the stages of development of the modern horse over time. What is the name of the process by which, over time, a species can change a characteristic.
Learners watch a short video showing some of the methods used to monitor the populations of species. Sketch a theoretical scenario of an environmental change that is likely to affect a specific population of a species (with local details, if possible) and explain to learners that they are going to plan how to monitor the impact of the environmental change on the species.
Earth and beyond
The movement of today's continents from the paleocontinent of Pangea can be modeled using a continental jigsaw diagram. World maps showing active volcanoes and earthquakes can be used to provide evidence for tectonic plate boundaries. The collision of a Mars-sized object with a young Earth can be demonstrated using a computer simulation available online.
Some students may believe that the Earth and the Moon have remained the same throughout time. The formation of stars in the nebula can be demonstrated with a computer simulation video available online.
Suggested activities
This can be reinforced by showing students an animation of the continents moving over time. Now show the students a map of the magnetic strips on either side of the Mid-Atlantic Ridge. Discuss with students that the syrup represents the runny part of the crust and the cookie the hard outer layer (crust and top crust).
How did the planets form? of debris left over from the formation of the Sun). If the Moon and Earth formed from the same accretion (debris) disk, how would their chemistry. we would expect the composition of the moon to be almost identical to the composition of the earth).
Plan
Why are common symbols used in circuit diagrams. so that scientists from various fields can more easily understand and interpret circuit diagrams). Why are connecting wires usually shown as vertical and horizontal lines on circuit diagrams. this makes it easier to interpret circuit diagrams and build circuits using them). Provide students with 4 circuit diagrams (each containing at least 2 components) and equipment to make circuits.
Resources: Range of circuit diagrams Cells, wires, switches, bulbs, buzzers, ammeters Resistors, variable resistors, voltmeters Photographs of 4 electrical circuits if needed. Once you are satisfied that the students are confident with making the circuits, make 4 circles around the room for the students to practice drawing circuit diagrams.