Can an experiment answer this question?

Question and prediction

A small school cart rolls down a low cardboard ramp and along a table. It seems to travel farther on smooth paper than on fabric. But «seems» is not a measurement. Before reading, predict which surface gives a shorter distance to rest, and say why.

New words without gaps

A research question names what we change and what we measure. The independent variable is the covering on the horizontal run; the dependent variable is distance from ramp exit to rest. Controlled conditions are the same cart, release height, ramp and method of release. A prediction is written before testing so evidence can challenge it. Friction may slow the wheels, but the distance alone does not give the friction force.

Work through supplied data

Working question: “How does replacing paper with fabric change the distance travelled by one cart after an identical descent?” Supplied practice numbers for this block are 82, 84, 83 cm on paper and 44, 46, 45 cm on fabric. They were invented for teaching; nobody claims to have measured them.

Test safely

Sketch both runs and label the start line. Name the changing covering and four conditions kept alike. If using a real cart, keep the low ramp stable on a clear table, well away from its edge, with a soft stop. Without equipment, use the supplied data and label them as such.

A common mistake

Mistake: saying fabric is “better” without choosing a goal: a long run or a short stopping distance. Transfer: if you replace the cart with a marble, which conditions must be defined again? Why can the answer not simply carry over?

Support diagram

Check your understanding

Close the text and explain the left-to-right drawing to a new learner. Name an observation, a teaching assumption and something the evidence does not prove. Then answer the transfer question without a hint and check units or direction against the diagram. If you disagree, return to the first unfamiliar word rather than memorising a sentence. A spoken explanation, a drawing and a measurement are different kinds of evidence: label each honestly.

Lab notebook page

Add a line to My World Lab Notebook: question → prediction → controlled conditions → changed condition → observation or calculation → conclusion → limit. Put a scale on a drawing or mark it ‘schematic’. If you ran no experiment, write ‘supplied calculation’, not ‘we measured’. Revisit the entry after the next lesson and note what became clearer.

Next lesson: Where does a measurement begin?