Activity—Limits of Measurement

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Presentation transcript:

Activity—Limits of Measurement Classroom Activity

(1) Engagement Question: For the graduated cylinders shown below, what is the BEST answer for the volume of liquid shown? (A) 50 ml (B) 54 ml (C) 53 ml (D) 52.8 ml (E) 52.85 ml

(6) Why might this ruler offer an advantage over the first ruler? Black block (2)PAPER RULER Closest measurement = 4cm Estimated @ _____ (3)PLASTIC RULER Closest measurement = 3.8 cm (6) Why might this ruler offer an advantage over the first ruler? More markings between 3 and 4 cm Can now identify 0.1 cm’s or 1mm

(4 & 5) Counting Tick Marks Inches Plastic ruler = 15 Example Ruler = 7 Centimeters (cm) Plastic ruler = 9 Example Ruler = 9 Minor Scale

Precision & Uncertainty All measurements involve some degree of estimation. The more lines on a measuring tool (the lines are called graduations) the less of an estimate you have to make and the more “certain” you will be in your measurement. We call a measuring instrument that allows you to measure exactly (with certainty) a PRECISE measuring instrument. Measurements that are not precise are said to have a greater uncertainty. Uncertainty is normally NOT caused by the person doing the measurement but rather from the instrument itself.

(8, 9 & 10) Graduated Cylinders Maximum Volume (mL) Major Scale (mL) Minor Scale (mL) Volume present (mL) 1000 100 10 570 100 10 1 47 0.2 or 0.1 7.2

(11) Ranking Graduated Cylinder Precision Greatest to least Precise 10ml 100ml 1000ml Why? 10 ml has a smaller minor scale than the others

(12) …how many digits after the decimal should be shown on your volume reading for the elicitation question (# 1)? Explain why. Was your original answer correct or not? 52.8 ml is correct Can only estimate one place past the minor scale or Can only estimate to the tenths place

(13) Why would 52.85 ml be an incorrect reading for the volume contained in the graduated cylinder? Can only estimate one place past the minor scale or Can only estimate to the tenths place

(14) …The measurements are recorded as: (A) 8 cm. (B) 8. 1 cm. (C) 8 (14) …The measurements are recorded as: (A) 8 cm (B) 8.1 cm (C) 8.12 cm. Which of the instruments (A, B or C) is probably the MOST PRECISE? Explain your reasoning. C Has more significant figures

(15) Explain how you can tell whether an instrument is precise by looking at the instrument itself. The instrument has a small minor scale

(15 continued) Explain how you can tell whether an instrument is precise by looking at the data produced by the instrument. The data has more significant figures