Hands-On Science Experiments

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Place 1 cup of raw peanuts in mortar and pestle (or ziplock bag).
2. Crush the peanuts thoroughly until they form a paste. This may take 5-10 minutes of grinding.
3. Continue grinding until you notice oil beginning to separate from the peanut solids.
4. Place the crushed peanut paste in the center of a coffee filter or cheesecloth.
5. Fold the filter and squeeze firmly over the glass jar to extract the oil.
6. Observe the oil collected in the jar. Note its color, consistency, and amount.
7. Test the oil's properties: Does it feel slippery? Does it leave a stain on paper?

🔬 Scientific Explanation

Peanuts are rich in lipids (fats and oils) stored in the seed for energy. When you crush the peanuts, you break open plant cells, releasing the oil from specialized structures called oil bodies. The mechanical pressure forces the oil to separate from the solid protein and carbohydrate components. This is similar to the industrial cold-press method used to extract cooking oils.

Dr. Carver used this basic principle but refined it with heat, chemical solvents, and pressure to extract oil more efficiently for industrial applications.

🔄 Variations to Try

• Try extracting oil from different nuts (almonds, walnuts, cashews) and compare yields
• Experiment with roasted vs. raw peanuts - does roasting affect oil extraction?
• Try adding gentle heat (warm water bath) to see if it increases oil yield
• Compare hand-crushing versus using a food processor

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Chop your chosen plant material into small pieces (1 cup chopped cabbage, beets, or 2 tablespoons turmeric).
2. Add plant material to pot with 2-3 cups of water.
3. Bring water to a boil, then reduce to simmer for 30-45 minutes until water is deeply colored.
4. Strain out the plant material, keeping the colored liquid (your dye).
5. While dye is still warm, add your white fabric strips to the dye bath.
6. Let fabric soak for 30 minutes, stirring occasionally for even coverage.
7. Remove fabric and rinse in cool water until water runs clear.
8. Hang fabric to dry and observe the final color.

🔬 Scientific Explanation

Plants contain pigments (colored molecules) used for photosynthesis, attracting pollinators, and protection. When you boil plant material, heat breaks down cell walls and releases these pigments into the water. Common pigments include anthocyanins (purple/red), carotenoids (yellow/orange), and chlorophyll (green).

Cotton fibers absorb the dye molecules through a combination of physical absorption and weak chemical bonding. Dr. Carver experimented with various mordants (metal salts) to make these bonds stronger and more permanent.

🔄 Variations to Try

• Test different plants: onion skins (orange), spinach (green), blackberries (purple)
• Add vinegar or baking soda to the dye bath - does it change the color?
• Try dyeing different materials: cotton, wool, silk, paper
• Experiment with mordants: add 1 tablespoon of salt or alum to make colors more permanent
• Create patterns by tying fabric before dyeing (tie-dye technique)

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Chop red cabbage into small pieces and place in a bowl.
2. Pour boiling water over cabbage and let steep for 10 minutes until water turns deep purple.
3. Strain the liquid - this is your pH indicator. It should be purple at neutral pH.
4. For each soil sample, mix 2 tablespoons of soil with 1/4 cup distilled water in a container.
5. Stir well and let settle for 5 minutes.
6. Filter the soil mixture through a coffee filter to get clear liquid.
7. Add 2 tablespoons of cabbage indicator to each soil water sample.
8. Observe the color change: Pink/Red = acidic, Purple = neutral, Blue/Green = alkaline.

🔬 Scientific Explanation

pH measures how acidic or alkaline a substance is on a scale from 0-14. Red cabbage contains anthocyanin, a pigment that changes color depending on pH. In acidic conditions, anthocyanins appear red/pink; in alkaline conditions, they appear blue/green.

Soil pH affects nutrient availability to plants. Dr. Carver understood that different crops thrive in different pH ranges. For example, peanuts prefer slightly acidic soil (pH 5.9-6.3), while sweet potatoes tolerate a wider range (pH 5.0-6.5). Testing soil pH helped Carver recommend appropriate crops for specific fields.

🔄 Variations to Try

• Test soil from different locations: garden, forest, near roads, under trees
• Create a pH reference chart using vinegar (acidic) and baking soda solution (alkaline)
• Test other substances: tap water, rainwater, orange juice, milk
• Monitor how adding compost or fertilizer changes soil pH over time
• Try other natural pH indicators: beet juice, turmeric, or blueberry juice

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Have an adult cut the top third off both plastic bottles to create open containers.
2. Poke small drainage holes in the bottom of each bottle.
3. Add a 2-inch layer of soil to the bottom of each bottle.
4. In one bottle (experimental), add layers: chopped vegetable scraps, soil, dry leaves, soil. Keep layers moist but not soggy.
5. In the second bottle (control), add only soil - no organic waste.
6. Place both bottles in a warm location with indirect sunlight.
7. Monitor daily: Check temperature, moisture, appearance, and smell.
8. Stir the compost every 2-3 days to add oxygen.
9. Add water if mixture becomes too dry (should feel like a wrung-out sponge).
10. Record observations in your science journal for 2 weeks.

🔬 Scientific Explanation

Composting is decomposition accelerated by providing ideal conditions for bacteria, fungi, and other decomposers. These microorganisms break down complex organic molecules into simpler compounds. The process requires four key elements: carbon (brown materials like leaves), nitrogen (green materials like food scraps), oxygen (from stirring), and water.

As decomposers consume organic matter, they release heat, carbon dioxide, and nutrients. The final product - compost - is rich in nitrogen, phosphorus, and potassium, the same nutrients Carver knew were depleted from cotton farming. By returning organic matter to soil, farmers could restore fertility naturally and sustainably.

🔄 Variations to Try

• Compare composting with and without mixing (testing oxygen's role)
• Try different carbon-to-nitrogen ratios (more leaves vs. more food scraps)
• Test different moisture levels
• Add a small amount of finished compost as a "starter" to introduce beneficial microbes
• Compare decomposition rates at different temperatures

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Label 6 pots: "Control - Soil Only", "Compost - Light", "Compost - Heavy", "Fertilizer - Half Strength", "Fertilizer - Full Strength", "Sand/Poor Soil"
2. Fill pots according to labels: Control (100% potting soil), Compost Light (75% soil, 25% compost), Compost Heavy (50% soil, 50% compost), etc.
3. Plant 3 seeds in each pot at the depth recommended on seed packet.
4. Water all pots equally with same amount of water.
5. Place all pots in the same location with equal light and temperature.
6. Water equally every 2-3 days or as needed to keep soil moist.
7. Measure and record: Days until germination, plant height every 3 days, leaf color and number, overall plant health.
8. After 2-3 weeks, compare final results across all conditions.

🔬 Scientific Explanation

Plants require macronutrients (nitrogen, phosphorus, potassium) and micronutrients for healthy growth. Nitrogen promotes leafy green growth, phosphorus supports root development, and potassium aids overall plant health. When soil is depleted of these nutrients - as cotton farming did in the South - plants cannot thrive.

Compost provides slow-release nutrients plus beneficial microorganisms. Commercial fertilizers provide concentrated nutrients but no organic matter. Dr. Carver advocated for compost and crop rotation to restore soil naturally, understanding that healthy soil creates healthy plants.

🔄 Variations to Try

• Test different types of plants (legumes vs. non-legumes)
• Try various organic amendments: coffee grounds, eggshells, leaf mulch
• Compare results with different watering schedules
• Test the effect of pH by adding lime or sulfur to some pots
• Grow peanuts or sweet potatoes to replicate Carver's crops

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Prepare food samples: Mix small amount of each food with water to create liquid samples (1 part food to 3 parts water).
2. Label test tubes for each food sample.
3. Add 2 ml of each food solution to its labeled test tube.
4. Add 2 ml of water to one tube as a negative control.
5. Carefully add 1 ml of Biuret reagent to each tube.
6. Gently swirl tubes to mix (do not shake vigorously).
7. Wait 2-3 minutes and observe color changes.
8. Record results: Blue = no protein, Violet/Purple = protein present. Darker purple = more protein.

🔬 Scientific Explanation

The Biuret test detects proteins by reacting with peptide bonds that link amino acids together. When Biuret reagent (copper sulfate in alkaline solution) contacts protein, copper ions form complexes with nitrogen atoms in the peptide bonds, creating a characteristic violet color.

Dr. Carver understood that protein was essential for human nutrition and that many poor Southern families suffered from protein deficiency. Peanuts, with 25-30% protein by weight, offered an affordable protein source that could be grown locally. This knowledge drove Carver's promotion of peanuts and development of peanut-based foods.

🔄 Variations to Try

• Test various nuts: almonds, walnuts, cashews - compare protein levels
• Compare fresh vs. cooked foods (does cooking affect protein detection?)
• Test different beans and legumes that Carver studied
• Create a protein concentration series to see gradual color change
• Test plant-based vs. animal-based protein sources

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Cut small pieces of each food sample (about 1 inch square).
2. Arrange food samples on white plate or paper, leaving space between each.
3. Label each sample clearly.
4. Using the dropper, place 2-3 drops of iodine solution on each food sample.
5. Wait 30 seconds and observe color changes.
6. Record results: Blue-black color = starch present, Brown/yellow = no starch (iodine's natural color).
7. Compare the intensity of color change across different foods.

🔬 Scientific Explanation

Starch is a complex carbohydrate made of long chains of glucose molecules. Iodine reacts with starch by fitting inside the helical structure of amylose (a component of starch), creating a blue-black starch-iodine complex. This color change is highly specific to starch and doesn't occur with simple sugars.

Dr. Carver extracted starch from sweet potatoes to create flour, laundry starch, and other products. By identifying high-starch crops and developing extraction methods, Carver helped farmers create value-added products from their harvests, increasing farm income beyond simply selling raw crops.

🔄 Variations to Try

• Test leaves from different plants - which photosynthesize and store starch?
• Compare ripe vs. unripe bananas (starch converts to sugar during ripening)
• Test the effect of cooking on starch (raw vs. cooked potato)
• Examine different types of flour and grains
• Test fruits at different stages of ripeness

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Tear spinach leaves into small pieces and place in mortar (or plastic bag).
2. Add 2 tablespoons of rubbing alcohol and grind leaves thoroughly until liquid is dark green.
3. Cut coffee filter into strips about 1.5 inches wide and 6 inches long.
4. Draw a pencil line across the strip, 1 inch from the bottom.
5. Place a concentrated drop of the green plant extract on the pencil line. Let dry completely.
6. Repeat step 5 three more times (4 drops total), allowing drying between each application.
7. Pour rubbing alcohol into glass to a depth of 0.5 inches.
8. Hang the filter strip in the glass so the bottom touches the alcohol but the green dot stays above the liquid level.
9. Watch as the alcohol moves up the paper, carrying pigments with it.
10. When alcohol reaches near the top (20-30 minutes), remove strip and let dry.
11. Observe the separated color bands.

🔬 Scientific Explanation

Chromatography separates mixtures based on how different molecules interact with a solvent (alcohol) and a stationary surface (paper). Smaller, more soluble molecules travel farther up the paper, while larger or less soluble molecules remain closer to the starting point.

Plants contain multiple pigments that serve different functions: chlorophylls absorb light for photosynthesis, while carotenoids protect cells from sun damage and attract pollinators. Dr. Carver used similar analytical techniques to understand plant chemistry and develop dyes, paints, and stains from different plant pigments. His work showed that agricultural "waste" contained valuable chemical compounds.

🔄 Variations to Try

• Try leaves from different plants: red cabbage, flower petals, fall leaves
• Compare pigments from the same plant at different seasons
• Test whether different solvents (water vs. alcohol) separate pigments differently
• Try chromatography with food coloring to understand synthetic vs. natural pigments
• Measure how far each pigment travels and calculate "Rf values"

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Label 6 containers for different conditions: "Light + Moisture", "Dark + Moisture", "Light + Dry", "Cold + Moisture", "Warm + Moisture", "Control"
2. Line each container with damp paper towel. Place 5 seeds in each container.
3. Cover seeds with another layer of damp paper towel.
4. Cover containers with plastic wrap to retain moisture.
5. Place containers in designated conditions: Light (windowsill), Dark (cupboard), Dry (no added water), Cold (refrigerator), Warm (near heater), Control (room temperature, indirect light).
6. Check daily. Add water as needed to keep towels damp (except "Dry" container).
7. Record daily observations: Number of seeds germinated, length of roots, length of shoots, general appearance.
8. After 7-10 days, compare germination rates and seedling growth across all conditions.

🔬 Scientific Explanation

Seed germination requires three essential factors: water (to activate enzymes and soften seed coat), optimal temperature (to support metabolic processes), and oxygen (for cellular respiration). Light is not required for germination itself but is needed once the seedling emerges for photosynthesis.

Water triggers the seed to break dormancy and begin using stored nutrients. Enzymes break down starches into sugars for energy. The embryo grows, pushing the root downward and shoot upward. Dr. Carver's germination studies helped determine the best planting times and conditions for crops in Alabama's climate, maximizing germination success for farmers.

🔄 Variations to Try

• Test different seed types: Compare peas, beans, corn, sunflower seeds
• Try different water pH levels (acidic vs. alkaline)
• Compare fresh seeds vs. old seeds (test seed viability)
• Test the effect of seed size on germination speed
• Try pre-soaking seeds vs. planting dry seeds

🎒 Materials Needed

📋 Step-by-Step Procedure

1. Fill all three pans with 2-3 inches of soil, packed gently but not too firmly.
2. Pan 1 (Bare Soil): Leave soil exposed with no cover.
3. Pan 2 (Grass Cover): Plant grass sod on top or thickly sprinkle grass seed and water daily for 1-2 weeks until established.
4. Pan 3 (Mulch Cover): Cover soil surface with 1 inch layer of leaves or mulch.
5. Elevate one end of each pan to create a 15-20 degree slope using blocks or books.
6. Position collection containers at the lower end of each pan to catch runoff.
7. Using watering can with sprinkler head, simulate rainfall by pouring 2 cups of water evenly over each pan from 12 inches above.
8. Observe and photograph erosion patterns, gully formation, and water runoff.
9. Measure the amount of water and soil collected in each container.
10. Compare soil loss across the three conditions.

🔬 Scientific Explanation

Soil erosion occurs when rainfall or wind removes topsoil, which contains most nutrients needed for plant growth. Without plant cover, raindrops strike bare soil with enough force to dislodge particles. Water then carries these particles downhill, creating gullies and removing fertile topsoil.

Plant roots hold soil in place mechanically. Plant leaves intercept rainfall, reducing impact force. Organic matter (from decomposing plants) improves soil structure, making it more resistant to erosion. Dr. Carver promoted crop rotation, cover crops, and maintaining ground cover because he understood that continuous cotton farming left soil bare for months, leading to catastrophic erosion. The South lost billions of tons of topsoil before Carver's conservation methods were widely adopted.

🔄 Variations to Try

• Test different slope angles (10, 20, 30 degrees) - does steeper slope increase erosion?
• Compare different types of ground cover: straw, wood chips, living plants
• Try different soil types: sandy, clay, loam
• Simulate different rainfall intensities (light sprinkle vs. heavy downpour)
• Add terracing or contour barriers to one pan to test erosion control structures