This unit establishes the habits used throughout the semester: careful observation, measurement, fair testing, evidence, and redesign. The student ends the unit by engineering a paper bridge.
Use Unit 1 Student Pages.
Time: 60 minutes Big question: How do we separate what we observe from what we think it means?
The student will:
- make observations using several senses;
- distinguish an observation from an inference;
- revise an inference when new evidence appears;
- explain why honest records matter.
Place four safe objects in separate opaque paper bags. Good choices include a spoon, cotton ball, toy car, pine cone, battery, key, or block. Close the bags with tape. Do not use food, liquids, sharp items, or anything easily recognized by smell if allergies are possible.
Print Student Page 1.
- four mystery bags;
- pencil;
- optional magnifying glass;
- ruler;
- Student Page 1.
Read or paraphrase Proverbs 18:13. Explain:
It is wise to listen and investigate before deciding. In science, humility means separating what we actually notice from the explanation we are forming.
An observation is information gathered with senses or tools: "The object is 12 centimeters long." An inference is a reasonable interpretation: "It may be a spoon." Inferences are useful, but they can change when evidence changes.
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Put one mystery bag on the table.
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Say:
Describe only what you can sense without naming the object.
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Let the student feel, listen to, smell, and gently move the bag.
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If the student says, "It is a key," respond:
That may be a good inference. What observation led you there?
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Record at least three observations and one inference for each bag.
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Ask the student to rank confidence from 1 to 5.
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Open one bag at a time. Add a final observation after looking.
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Discuss which clues were strong and which were misleading.
The student will sometimes name the object before describing evidence. That is normal. The key learning is that a plausible inference is not the same as an observation.
Ask:
- "What can you tell about shape?"
- "Does it bend?"
- "Is it smooth or rough?"
- "Does it make a sound?"
- "Can a ruler give us another observation?"
Do not say, "Wrong guess." Say:
That inference did not match the object. Which clue led us away from it?
Ask:
- Which observation was most useful?
- Did a high-confidence inference ever turn out to be wrong?
- Why should a scientist write what happened instead of what was expected?
Complete Student Page 1. End with one sentence:
Evidence can change my mind because ______________________________.
The student chooses a fifth object and runs the mystery test for the parent, correctly labeling the parent's statements as observations or inferences.
Time: 65 minutes Big question: Which measurements help us compare materials?
The student will:
- compare objects by observable properties;
- measure length, mass, and volume where appropriate;
- organize measurements in a table;
- understand that different properties answer different questions.
Collect six objects made of different materials, such as a wooden craft stick, metal spoon, plastic block, rubber eraser, sponge, and stone. If available, set out a kitchen scale. Fill a measuring cup with enough water to test absorption, not displacement.
Print Student Page 2.
Keep water away from electronics. Do not test objects that could dissolve, splinter, rust significantly, or be damaged.
Say:
Creation contains both variety and dependable properties. Careful measurement helps us describe that variety truthfully rather than relying only on first impressions.
Matter takes up space and has mass. Materials may be compared by properties such as texture, flexibility, hardness, absorbency, length, and mass. A property is useful when it helps answer a design question. "Best material" is incomplete unless we know what the material must do.
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Let the student sort the objects in any way.
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Ask:
What rule did you use for your groups?
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Re-sort by material, flexibility, texture, or another property.
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Estimate and then measure each object's length.
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If a scale is available, estimate and measure mass in grams.
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Test flexibility gently and record low, medium, or high.
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Place three safe objects in 15 milliliters of water for ten seconds. Record whether each absorbs water.
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Ask which measurements would matter for:
- a raincoat;
- a bridge;
- a pillow;
- a cooking spoon.
The heaviest material will not always be the hardest, and the longest will not always have the greatest mass. The sponge may absorb water and also be lighter than objects that do not.
Say:
A number without a unit is incomplete. "Ten" could mean centimeters, grams, or milliliters. Let us name what the number measures.
For this lesson:
- centimeters measure length;
- grams measure mass;
- milliliters measure liquid volume.
Ask:
- Which object surprised you?
- Which property would matter most for a bridge deck?
- Can one material be useful for one job and poor for another?
Complete Student Page 2 and write:
I would choose __________ for __________ because its property of __________ would help.
Design a fair test for hardness or water resistance. The student must explain how to keep the test from damaging objects or producing an unfair comparison.
Time: 65 minutes Big question: How can we tell what caused a result?
The student will:
- identify a variable to change;
- identify conditions to keep the same;
- run repeated trials;
- make a simple graph and evidence-based claim.
Make a cardboard ramp approximately 45-60 centimeters long. Gather a toy car, books, tape measure, and tape. Choose a smooth floor area with at least two meters of open space.
Print Student Page 3.
Keep the travel path clear. Do not use stairs or launch toward people, pets, glass, or furniture.
Refer to Proverbs 12:22 and say:
We honor truth by recording every trial, not only the trials we like. A fair test helps us avoid claiming more than our evidence can show.
The student will change ramp height and measure distance traveled. The car, ramp, release point, surface, and measuring method should stay the same. Repeated trials reveal ordinary variation.
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Show the car and ramp. Ask:
What could affect how far this car travels?
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List ideas. Circle ramp height.
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Say:
Today we will change ramp height only. What must stay the same?
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Mark the release point. Do not push the car.
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Test a low ramp height three times. Measure from the ramp's end to the car's stopping point.
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Repeat for medium and high heights.
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Graph the middle result from each height or choose the most typical result.
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Let the student inspect any unusual trial instead of erasing it.
The higher ramp will usually produce greater travel distance because the car begins with more stored energy related to its position. Surface irregularities, wheel alignment, and release differences can create variation.
Check:
- Is the ramp slipping?
- Is the car released from the same line?
- Is someone pushing?
- Is the floor level and clear?
- Are measurements beginning at the same place?
Then repeat one set. Do not promise perfectly identical trials.
Avoid "The high ramp makes it faster" unless speed was measured. You measured distance, not speed. Say:
The car traveled farther in our test.
Have the student complete:
- Claim: A higher ramp caused...
- Evidence: At the low height..., while at the high height...
- Reasoning: Changing height mattered because...
Complete Student Page 3, including the bar graph.
Design a second investigation that changes surface type while keeping ramp height constant. Save it for Lesson 11 if desired.
Time: 75 minutes Big question: How can shape make a weak material stronger?
The student will:
- define measurable design criteria;
- compare structural shapes;
- build and test a prototype;
- revise a design using evidence.
Place two equal stacks of books 20 centimeters apart. Gather printer paper, index cards, tape, ruler, and at least 40 identical coins or washers.
Print Student Page 4 and the reusable Engineering Design Page.
- The bridge must span 20 centimeters.
- It may touch only the two supports.
- Use at most two sheets of paper and 30 centimeters of tape.
- It must hold coins for five seconds.
- Coins must be placed near the center, one at a time.
Adjust the gap if the available paper is too short.
Refer to Mark 12:31 and say:
Engineers use creativity to meet real needs. Today our bridge is a model, but careful design becomes especially meaningful when it helps people safely.
Flat paper bends easily. Folding, rolling, or corrugating the paper changes its shape and can increase stiffness. The amount of material has not changed much, but its arrangement has.
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Lay one flat sheet across the gap and test it with coins.
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Ask:
What failed first? Where did the shape change?
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Show, but do not build, three shape ideas:
- accordion folds;
- rolled tubes;
- folded side rails.
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Give eight minutes for sketching two designs.
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Ask the student to choose one and predict its coin capacity.
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Build Prototype 1.
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Test slowly. Stop if coins may scatter dangerously.
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Record capacity and failure location.
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Ask:
What is one change supported by the test?
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Build or modify Prototype 2 and retest under the same rules.
A folded, rolled, or layered shape will usually hold more than a flat sheet. Exact capacity depends on folds, tape, paper, span, and coin placement.
Say:
I see an idea, but this is your design. Would you like a question, a hint, or time to think?
If a hint is requested:
Look at the place where it bent. How could the shape resist bending there?
Reduce the span to 15 centimeters for one test, or help the student create one clean fold. Then return control to the student.
Ask:
- What changed between the prototypes?
- How much did capacity change?
- Which part carried the load?
- Was the strongest design also the simplest?
- What would a real bridge engineer need to consider that our model ignored?
Complete Student Page 4 and the Engineering Design Page.
Ask the student to explain these words using examples from the unit:
- observation;
- inference;
- property;
- fair test;
- evidence;
- prototype;
- revision.
Complete Progress Notes.
Build a third bridge with a new constraint: one sheet of paper, no tape, or a 30-centimeter span. Compare efficiency as coins held per sheet of paper.