Article: The easiest materials to start with include chert, flint (a subtype of chert), and obsidian. These all leave smooth surfaces behind when fractured, require comparatively little force to chip, and usually have a uniform, fine grain. Once you've made a few small objects with these, you can experiment with materials that are a bit more difficult to work with, including basalt, lab-manufactured quartz, glass from the bottom of a wine bottle, and some types of porcelain.  Tap the material with a hard object. Generally speaking, the higher the pitch you hear, the better it is for knapping.  You can find many of these on eBay, or you can look for the right stones in nature if you have a geological guide to your local area. However, do not disturb piles of stone or stone surrounded by flakes and fragments. These are part of the archaeological record and should be left undisturbed. Select a stone that has few, if any, large cracks, fissures, bubbles, significant grain, noticeable inclusions (traces of other minerals), or other irregularities which would likely cause it to break or flake off in ways contrary to the shape you are trying to achieve. When it comes to size and shape, you have two options:  A flake is ready to be turned into an arrowhead or other tool. These are slightly convex, and relatively small. A core is a large stone, which you can break to create flakes. If you're hunting on your own, you'll likely have to start with one of these. Note that the term "preform" can refer to either of the above stages. The term means a material that has not yet been formed into a tool. If you are working with a ready-made flake, all you need is a pressure flaker, typically an antler tine or copper nail set in a wooden handle. If you have a core, you'll also need a more powerful striking tool, either a cylindrical "billet" or simply a dense, round stone that fits your hand (a hammerstone). A piece of limestone or other stone softer than your material, or an old grinding wheel, is also required if you are starting with a core.  See the Tips section below for more information on choosing billets and pressure flakers. A pressure flaker tool at least 1 ft (0.3 m) long will give you more control and reduce the risk of "tennis elbow" from repeated use. A smaller one may be easier to use for your first attempt, however. You'll be handling sharp, broken stone, and sending fragments of it flying. Goggles and thick, long pants are essential. Wear long sleeves and gloves as well, or expect to receive cuts and scrapes. A piece of leather to drape over your leg, and a smaller one to hold your materials with, are recommended. Always work outdoors in an open area, away from structure, or in a ventilated area with a high-powered fan constantly blowing away from your face. Stone dust is extremely sharp and can damage lungs and eyes over time, especially in an area of still air where it creates clouds of dust. Work over a tarp or cloth, so you can gather up and discard the fragments once you are done. Fragments left on the ground can cut feet. You can knap on a table or bench, of course, but traditionally knapping is done sitting cross-legged, with the stone in one hand in one's lap.  This method can be difficult for beginners.  Experiment to find out which sitting position gives you the most control, especially with pressure flaking.  If you have a core, continue on to the next step, "create a flat platform," or to "use direct percussion" below that if you already have a flat side on your core. If you have a flake, continue on to "abrade the edge" below, or directly to the section on pressure flaking if you bought a ready-made flake with a thick, dull edge. Large, heavy stones may require a table or a large, flat stone – but better yet, pick something smaller for your first project.
Question: What is a summary of what this article is about?
Select a material for shaping. Choose a suitable piece. Gather your flintknapping tools. Wear protective clothing. Work in ventilated areas. Sit comfortably.
Article: This is one time when you want to be ahead of the curve. Pregnancy is full of unexpected events, and one of those may mean needing to head to the hospital before you thought. So don't wait until your thirty-sixth week––pack for any unexpected occasion, early on. This is especially important if your pregnancy is considered high-risk (e.g. expecting multiple births). For a low-risk pregnancy, start packing around 30 to 35 weeks. If you are having a scheduled induction or C-section, pack at least two to three weeks in advance. There are things you may need to take to the hospital that might not be necessary to worry about at home. Sometimes your birthing location has rules in place regarding what they will allow in the labour room. For example, to protect your car in case your water breaks while driving, sit on a towel with a bin liner beneath it. Also, use a waterproof mattress pad to protect your bed--it's very likely to happen when you're in bed. Incontinence pads (available at drugstores and retail stores) are also useful and great for use for babies. Have plenty of towels: You may really need them if your water breaks on the way to the hospital. Pack another towel so you can have a quick wash if you want to.
Question: What is a summary of what this article is about?
Don't procrastinate! Consider your birthing location. Find out what your birthing location (if away from home) will and will not provide and allow. Protect certain surfaces in case your waters break.