Hello everyone, today's topic is about drawing straight lines. Straight lines, there are horizontal lines and vertical lines. We are going to talk about the techniques for drawing short lines and the one for drawing long lines, there is a difference there. After we have lines that are vertical, horizontal, long and short, you will be able to draw the grids, right angles, squares and parallelograms. These are very basic and very important techniques, because almost all 2D graphics are made up of these lines. Now, first, get a pencil ready. It will be best to have a B pencil. Pencils, we have a HB graphite scale. H stands for hard while B, which is softer, stands for black. Then, try to shape the tip of the pencil to such a cone shape. Prepare a piece of paper, ordinary A4 printing paper or copier paper will do. Or if you buy those 5mm square papers from stationary shop, that will also be very convenient, it can let you practice well. So get a B pencil and a piece of paper. Let us try to draw a horizontal line first. Let me first not talk about the technique, just use your own way, think about how you are going to use your pencil and draw a horizontal line on paper. After you are through, try this horizontal line, you can see here, I've put a darker one, and a fainter one. Both types are quite important. Pencils, when you apply more force, you get darker lines, if you draw lightly, you get a fainter line. Both techniques are important. Usually we use fainter lines to sketch, After that, we use darker lines to trace the important lines, and give the final result. So, during your practice, you will have the darker lines and the fainter lines. The concept is that, we have one type, that is the solid lines and the other is the construction lines. We need a lot of practice. I believe you have all tried to draw the lines. Now I am going to tell you how to draw it nicely. I can give you some tips, but you still need a lot of practice. First step, decide if this is a long line or a short line. Short lines depend on the movement of our wrist. This is the first important tip. If your line is longer, then, when you draw, you must move your arm, but not wave our arm. So you move the whole arm, instead of the wrist. For short lines, move your wrist; for long lines, move your arm. Here is another tip, first, plot the starting point and the finishing point. Then, don't touch the paper with your pencil tip, place the tip above the paper and draw in the air, move back and forth, back and forth between the points a few times, so that, your muscles remember this movement. Then, you actually draw. Place the pencil tip at the starting point and keep your eyes on the finishing point and draw. When you draw a line in such a way, it will be easy to draw it straight. Then, let me demonstrate how to draw vertical lines. Well, easy, turn your paper 90°, then draw a horizontal line, now it is vertical. Don't just draw the lines vertically, because that's not going to be easy. Make it a horizontal line instead. Our human muscles, when we draw horizontal lines, the coordination of our eyes and hands is much better than when we are drawing vertical lines. Then, what about incline lines? Well, same as horizontal line. Actually our arms are most suitable for drawing incline lines. Of course, the ability may differ slightly in different individuals, but I believe we can all find our own angles for drawing straight lines, one that is most suitable to each individual. If we are right-handed, then, a line from left down corner to right up corner will be the easiest angle for us. Of course, for horizontal lines, you can tilt the paper a bit and draw. Also for vertical lines, tilt the paper and draw. You need to know that, when you are going to draw longer, more important lines, you should use the angle that you are most comfortable with, the best way for your muscle to move and for your eyes and hands to coordinate, and you draw. So, let us practice. Get your papers. First, draw a frame. In learning Engineering Graphics, we usually start with drawing a frame with ruler. Here in this course, we don't emphasis on ruler and compass, therefore, I expect to see you draw a frame with just your pencil. Try, as you draw the frame, you will realise that a frame is just long lines. If you cannot draw like I have instructed, from starting point to finishing point, in one go, like the way we practiced just now, Then, you can break a long line with several points. It will be, from starting point to finishing point, starting to finishing, starting to finishing... and made up such a long straight line. This will be extremely simple, everyone can do it even without a lot of talents. If you use the right technique, with a lot of practice, it cannot be hard. Well, I also would like you to try and plot the grids. You can either draw squares or diamonds. In the same way, draw a lot of parallel lines, then, turn the paper and draw more parallel lines. All these practices will help you to be familiar with the drawing techniques. Parallel lines also need good coordination between eyes and hands. Therefore, if you will practice a few more times today, use that paper and pencil and practice, then, later when we learn more complicated technique of drawing, you will see that, mastering this technique of drawing lines will definitely help you a lot. So, practice how to draw right angles, squares, and parallelograms. I hope everyone has got their papers ready, try and draw rectangles, parallelograms, or squares. Try this: first, use the fainter lines to sketch, the construction lines, for reference. Then, darken it. And try all these: right angles, triangles, squares and parallelograms. All these are good practices. Finally, I would like to draw a simple conclusion. Today, we have learn how to draw horizontal lines very quickly, and how to draw vertical lines. I also mentioned how to draw short lines with just the movement of our wrist. But for longer lines, you need your muscles, and the coordination between your eyes and hands. Then, after having the short lines and long lines, it will be easy for you to draw grids, right-angled triangles, parallelograms, and squares. Well, all these are basic techniques, I have given you the key notes, but actually, it still depends on your practice, practice, practice.