Kitchen and everyday life · Some practice · about 20 minutes of practice

Basic Knife Skills

A sharp knife and a few good habits make cutting faster and safer. This guide covers how to hold the knife, how to hold the food, and how to wash and put knives away.

When to teach it: Watch from about 6, cut with an adult right beside you from about 8, and use a chef's knife alone from about 12.

You'll need

Chef's knife (8 to 10 inches), which handles most cutting jobs
Paring knife (3 to 4 inches) for small jobs
Cutting board
Damp kitchen towel, or a board with rubber feet
Practice foods like a zucchini, cucumber or potato

Before you start

Put a damp towel under the cutting board, or use a board with rubber feet, so it can't slide.
Always cut on a cutting board. Never cut food while holding it in your hand.

Physics

How it works: Why a sharp knife cuts with less force

Pressure is how much force pushes on each bit of area. The formula is pressure = force ÷ area. Push with the same force on a smaller area, and the pressure goes up.

A sharp knife's edge is very thin, so it touches the food along a tiny area. A small push makes a big pressure, and the food splits apart. A dull edge is wider and rounder. The same push spreads out, so the knife squashes or slides instead of cutting.

Here's an example with made-up numbers. A 5-pound push on an edge touching 0.01 square inch makes 5 ÷ 0.01 = 500 pounds per square inch (psi). The same push on a duller edge touching 0.1 square inch makes only 50 psi.

That's why a sharp knife is safer. A dull knife needs more force, and extra force makes it easier for the blade to slip off the food.

pressure = force ÷ area

Try it: Press a wooden craft stick into a lump of modeling clay two ways, using the same gentle push: first flat side down, then thin edge down. The edge sinks much deeper because the same force is squeezed onto a smaller area.

Keep learning: Science

Teaching it to your kids

Practice the claw with no knife at all. Curl your fingers on a zucchini and 'walk' them back.
Start with a steady food, like a zucchini cut in half and set flat side down, and stay right beside your child.
Teach 'step back, don't catch' before the very first lesson.
Have them say the habit out loud: 'Board steady, claw hand, tip down.'

Tips

A serrated knife works well for bread and soft produce.
Keep knives sharp with a sharpening steel or a pull-through sharpener. Don't try to sharpen serrated knives at home.
Hold a few knives in your hand before you buy one, and pick the handle that feels comfortable.
Keep knives out of the dishwasher. Wash and dry them by hand.

Common mistakes

Mistake	Instead
Cutting food while holding it in the air.	Always set the food on the cutting board first.
Fingers flat on top of the food.	Curl them into a claw with your thumb tucked behind.
The board slides around.	Put a damp towel or a rubber-footed board underneath.
Round food rolls away.	Cut a flat side first and set it down on that side.
Pressing hard with a dull knife.	Sharpen it. A sharp knife needs less force and is less likely to slip.

Safe habits

Use a cutting board, never your hand.
Never try to catch a falling knife.
Never leave a knife in a sink of soapy water.
Carry knives blade down and pass them handle first.

Sources

Free how-to guides for families, with nothing to earn, pass or send in. They follow U.S. rules and sources; your owner's manual, product labels and state and local rules come first.