Scheme of Work Cambridge International as & a level

1 : Cell structure

Syllabus ref. and Key Concepts (KC)	Learning outcomes	Suggested teaching activities
1.1 The microscope in cell studies KC1 KC6	1.1 1 Make temporary preparations of cellular material suitable for viewing with a light microscope. 1.1 2 Draw cells from microscope slides and photomicrographs. 1.1 3 Calculate magnifications of images and actual sizes of specimens from drawings, photomicrographs and electron micrographs (scanning and transmission). 1.1 4 Use an eyepiece graticule and stage micrometer scale to make measurements and use the appropriate units, millimetre (mm), micrometre (μm) and nanometre (nm). 1.1 5 Define resolution and magnification and explain the differences between these terms, with reference to light microscopy and electron microscopy.	Provide learners with an unlabelled diagram of a light microscope. Host a class discussion to elicit some of the names of the key components, and discuss their features and functions. Learners reflect on their knowledge and make five recommendations for their future study on this topic. They write these on post-it notes, which they add to the class board. Learners consider the recommendations of others, and highlight common mistakes that learners make. (F) Host practical activities for learners to use a light microscope and develop their ability to produce scientific drawings. These may include preparing a temporary, stained mount of plant tissue, and using an eyepiece graticule and stage micrometer to measure prepared slides of cells. Collect and display class results for measuring cells on a board or screen. This will facilitate the discussion of themes such as variability of cell size and appropriate sample sizes. Learners watch a video on the use of light and/ or electron microscopy: http://bigpictureeducation.com/video-light-microscopy and http://bigpictureeducation.com/video-electron-microscopy. Learners list things ‘I knew’ in green and things that ‘are new’ in red in order to reflect on their knowledge. (I) Learners design a ‘step-by-step’ guide, perhaps targeted at learners who have not yet studied the topic, to use an eyepiece graticule and stage micrometer. This is in the form of a flow diagram with statements separated by arrows, a short story, or an animation produced on a computer. (I) Learners prepare a series of flashcards that help them interchange measurements. For example, a numerical value in millimetres (e.g. 0.05 mm) written on one side of the card, is restated in micrometres on the other side (e.g. 5 µm). Useful resources to help structure this activity are: https://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/ www.biology.arizona.edu/cell_bio/tutorials/cells/cells2.html www.exo.net/~pauld/summer_institute/Nano%20Institute/Day1%20Scale/SM_Lesson2Student.pdf (I)