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Lessons: 9
Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level)
Human Nutrition Part 1: Digestion
Follow a meal through the digestive system and learn how large food molecules are broken down into small ones your body can absorb, with clear animations at every step. You will learn: • Why large, insoluble molecules must be digested • The 5 stages: ingestion, digestion, absorption, assimilation, egestion • The organs of the alimentary canal and the helper organs • The mouth: chewing, saliva and amylase • Swallowing and peristalsis • The stomach: churning, pepsin and hydrochloric acid • The duodenum: pancreatic juice, bile and emulsification • Enzymes and their products • Physical vs chemical digestion (the bile mistake!) • Exam-style questions with answers This is part 1 of 2 in Human nutrition Part 1 – Digestion (this lesson) Part 2 – Absorption and assimilation © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Biology · v.1
Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level)
6.1 Line Segments: Midpoint, Length and Gradient
Learn how to find the midpoint, length and gradient of any line segment, step by step, with clear animations and worked examples. These three skills come up in almost every O Level Maths paper. You will learn: • A quick recap of coordinates, including negative numbers • The midpoint formula, and why it is just an average • The length of a line segment using Pythagoras' theorem (surds and 3 s.f.) • Gradient: positive, negative, zero and undefined • Calculating gradient as y step ÷ x step, as an exact fraction • Exam questions that work backwards: a missing end point and an unknown coordinate • Practice questions with full answers This is lesson 1 of 7 in Chapter 6: Graphs 6.1 Line segments (this lesson) 6.2 Straight-line graphs 6.3 Parallel and perpendicular lines 6.4 Travel graphs 6.5 Quadratic graphs 6.6 Gradient of a curve 6.7 Graphical solutions of equations © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Mathematics · v.1
Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level)
Human Nutrition Part 2: Absorption and Assimilation
Follow digested food out of the gut, into the blood and into your cells. Includes the three practicals you need for the exam. You will learn: • Absorption in the ileum and water absorption in the colon • Egestion vs excretion • How the ileum is adapted: length, folds, villi and microvilli • Inside a villus: capillaries and the lacteal • Diffusion, active transport and osmosis • The hepatic portal vein and the liver • Assimilation: how cells use glucose, fats and amino acids • Practical 1: amylase and starch • Practical 2: a model gut with Visking tubing • Practical 3: pepsin, acid and egg white • Exam-style questions with answers This is part 2 of 2 in Human nutrition Part 1 – Digestion Part 2 – Absorption and assimilation (this lesson) © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Biology · v.1
Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level)
6.2 Straight-Line Graphs: y = mx + c
Draw straight-line graphs, understand what m and c mean in y = mx + c, find the equation of a line, and solve simultaneous equations using graphs. You will learn: • Drawing a line from a table of values (with a safety-check point) • m is the gradient and c is the y-intercept • Rearranging equations into y = mx + c • Horizontal and vertical lines: y = 3 and x = −2 • Finding the equation from a gradient and a point, or from two points • Sketching a line quickly from its intercepts • Solving simultaneous equations with graphs • Practice questions with full answers This is lesson 2 of 7 in Chapter 6: Graphs 6.1 Line segments 6.2 Straight-line graphs (this lesson) 6.3 Parallel and perpendicular lines 6.4 Travel graphs 6.5 Quadratic graphs 6.6 Gradient of a curve 6.7 Graphical solutions of equations © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Mathematics · v.1
Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level)
6.3 Parallel and Perpendicular Lines
Watch a line turn through 90° and discover why perpendicular gradients multiply to −1. Then find the equations of parallel and perpendicular lines, and where lines meet. You will learn: • Parallel lines have equal gradients • The equation of a parallel line through a point • The perpendicular rule: flip the gradient and change its sign (negative reciprocal) • The common mistake of doing only half the rule • The equation of a perpendicular line • Finding where two lines meet • Testing whether two lines are perpendicular • Practice questions with full answers This is lesson 3 of 7 in Chapter 6: Graphs 6.1 Line segments 6.2 Straight-line graphs 6.3 Parallel and perpendicular lines (this lesson) 6.4 Travel graphs 6.5 Quadratic graphs 6.6 Gradient of a curve 6.7 Graphical solutions of equations © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Mathematics · v.1
Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level)
6.4 Travel Graphs: Distance–Time and Speed–Time
Travel graphs tell the story of a journey. Learn to read distance–time and speed–time graphs, work out speed and acceleration, and find the distance travelled from the area under a graph. You will learn: • Distance–time graphs: gradient = speed, flat line = stopped • Average speed = total distance ÷ total time (not the average of the speeds!) • Speed–time graphs: gradient = acceleration or deceleration • A flat line on a speed–time graph means steady speed, not stopped • Area under a speed–time graph = distance travelled • Telling the two graphs apart • Practice questions with full answers This is lesson 4 of 7 in Chapter 6: Graphs 6.1 Line segments 6.2 Straight-line graphs 6.3 Parallel and perpendicular lines 6.4 Travel graphs (this lesson) 6.5 Quadratic graphs 6.6 Gradient of a curve 6.7 Graphical solutions of equations © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Mathematics · v.1
Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level)
6.5 Quadratic Graphs: Parabolas, Roots and Turning Points
Graphs that curve! Draw and sketch quadratic graphs (parabolas), and find their roots, line of symmetry, turning point and y-intercept, from the graph and by completing the square. You will learn: • The parabola: U shape for positive x², n shape for negative x² • Drawing a quadratic graph from a table of values with a smooth curve • Key features: roots, line of symmetry, turning point, y-intercept • Finding the turning point by completing the square • A maximum turning point: the height of a thrown ball • Sketching a quadratic in four steps • Practice questions with full answers This is lesson 5 of 7 in Chapter 6: Graphs 6.1 Line segments 6.2 Straight-line graphs 6.3 Parallel and perpendicular lines 6.4 Travel graphs 6.5 Quadratic graphs (this lesson) 6.6 Gradient of a curve 6.7 Graphical solutions of equations © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Mathematics · v.1
Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level)
6.6 Gradient of a Curve, Asymptotes and Exponential Graphs
Meet cubic, reciprocal and exponential graphs, learn what an asymptote is, and estimate the gradient of a curve by drawing a tangent. You will learn: • Recognising cubic, reciprocal, squared reciprocal and exponential graphs • Asymptotes: lines a curve gets closer to but never touches • Exponential graphs like y = 2^x • Why the gradient of a curve keeps changing • What a tangent is • Estimating the gradient at a point using a tangent • Practice questions with full answers This is lesson 6 of 7 in Chapter 6: Graphs 6.1 Line segments 6.2 Straight-line graphs 6.3 Parallel and perpendicular lines 6.4 Travel graphs 6.5 Quadratic graphs 6.6 Gradient of a curve (this lesson) 6.7 Graphical solutions of equations © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Mathematics · v.1
Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level)
6.7 Solving Equations with Graphs
Where graphs cross, you find solutions! In the final lesson of Chapter 6, solve equations using graphs, including the exam favourite: which line should I draw? You will learn: • The big idea: solutions are where graphs cross • Solving f(x) = 0 and f(x) = k with a horizontal line • Estimating x³ = 20 with a cubic graph • Finding where a curve meets a straight line • Rearranging an equation to choose the right line to draw • Why graph answers are estimates • Practice questions with full answers This is lesson 7 of 7 in Chapter 6: Graphs 6.1 Line segments 6.2 Straight-line graphs 6.3 Parallel and perpendicular lines 6.4 Travel graphs 6.5 Quadratic graphs 6.6 Gradient of a curve 6.7 Graphical solutions of equations (this lesson) © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Mathematics · v.1