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Grind
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Use a safe mortar and pestle to grind spices and seeds, compare coarse and fine textures, and learn about friction, force, and particle size.

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Step-by-step guide to grind spices and seeds with a mortar and pestle

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What you need
Adult supervision required, magnifying glass, mortar and pestle, paper and pencil, spoon, two small bowls or plates, whole spices or seeds (for example peppercorns or coriander seeds)

Step 1

Wash your hands and clear a small workspace so everything stays tidy and safe.

Step 2

Choose one type of whole spice or seed to test for grinding.

Step 3

Put about one teaspoon of that spice into a small bowl.

Step 4

Use the magnifying glass to look closely at one whole seed and notice its shape and size.

Step 5

Draw or write one short note on your paper about what the whole seed looks like.

Step 6

Put one teaspoon of the spice into the mortar.

Step 7

Press down and twist the pestle gently 10 times to make a coarse grind.

Step 8

Spoon the coarse grind into a labeled bowl or plate.

Step 9

Put a fresh teaspoon of the spice into the mortar for a fine grind.

Step 10

Press the pestle firmly one time to feel how stronger force cracks the seed more.

Step 11

Grind the spice with steady circular motions for 60 seconds to make a fine powder.

Step 12

Spoon the fine powder into a different labeled bowl or plate so you can compare them.

Step 13

Rub a small pinch of the coarse grind and a small pinch of the fine grind between your fingers to compare texture and particle size.

Step 14

With an adult, wash and dry the mortar and pestle when you are finished.

Step 15

Share your finished creation on DIY.org.

Final steps

You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!

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Help!?

What can I use if I don't have a mortar and pestle or a magnifying glass?

If you don't have a mortar and pestle, use a clean small jar and a sturdy spoon or a rolling pin on a zip-top bag to press and twist for the 10 coarse twists and 60-second fine grind, and if you lack a magnifying glass use your phone camera zoom or a reading magnifier to inspect the whole seed.

My spice isn't getting fine after the 60 seconds — what should I try?

If the spice stays coarse after the 60-second circular grinding step, press a bit firmer, grind in shorter bursts while rocking the pestle, or dry the spice slightly and repeat the single firm 'press the pestle firmly one time' crack before continuing.

How can I adapt this activity for different ages?

For younger children, have an adult do the 'press the pestle firmly' step and guide the 10 gentle twists and the rubbing comparison while the child draws with the magnifying glass, and for older kids let them do the full 60-second fine grind, label bowls, time the grind, and write a short note to share on DIY.org.

How can we extend or personalize the experiment?

Extend the activity by testing and labeling three different whole spices side-by-side, photographing the magnified seed and your drawing to post on DIY.org, and using the coarse and fine grinds in a simple recipe like yogurt or toast to compare flavor and texture.

Watch videos on how to grind spices and seeds with a mortar and pestle

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Facts about kitchen science and basic physics

🌶️ Crushing spices releases aromatic oils, so ground spices often taste stronger and smell more intense than whole ones.

🔬 Finer particles have more surface area and usually dissolve or react faster than coarse pieces.

🌡️ Grinding produces frictional heat — if you grind long enough your mortar or mixture can get noticeably warm.

🗿 Mortar and pestle are among humanity’s oldest tools — ancient versions were used to crush food and make medicines.

🥜 Some seeds (like flax) must be ground so your body can access their nutrients instead of passing them whole.

How do I guide my child to grind spices and seeds with a mortar and pestle?

Start by selecting two or three spices or seeds (for example, peppercorns and coriander). Place a small amount in a sturdy, child-safe mortar. Demonstrate gentle presses, twisting and short taps with the pestle to make coarse crumbs, then increase pressure and speed to make finer powder. Let the child try different techniques, compare textures on a tray, and record observations. Clean up spills and wash tools after use.

What materials do I need to do this grinding activity with my child?

Gather a child-safe mortar and pestle (wooden, silicone, or heavy plastic), a selection of whole spices and seeds (e.g., peppercorns, coriander, cumin, flax), small bowls or trays for samples, measuring spoons, a spoon for transferring, a magnifying glass, paper and pencil to note textures, wet cloth for quick cleanup, and adult supervision. Optional: kitchen scale, timer, and a sieve to compare particle sizes.

What ages is the spice-and-seed grinding activity suitable for?

This activity suits preschoolers through elementary ages with adult supervision. Ages 3–5 can explore coarse grinding with a soft, lightweight pestle while an adult controls harder motions. Ages 6–9 can practice controlled force to make finer textures and record results. Older children (10+) can quantify particle sizes, time actions, or compare manual grinding to an electric grinder. Always supervise for choking risks and ensure safe tools.

What are the benefits of grinding spices with kids?

Grinding spices teaches science and practical life skills: children learn about friction, force, and particle size while improving hand strength and fine motor control. It boosts observation and vocabulary as kids compare coarse and fine textures and record results. The activity connects to cooking and cultures, encourages curiosity, and practices safe, supervised tool use. It also offers sensory exploration through smell and texture, supporting cognitive and sensory development.
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