Imagine that you have 3 fish tank thermometers.

• The BLUE one always reads the same temperature no matter how hot or cold the water is.
• The RED one shows a different temperature every time even if your last measurement was seconds earlier.
• The GREEN one seems to read accurately.

Based on this information, fill in the table below.

	Will it provide a consistent measurement?	Is it measuring what it’s supposed to measure?	Is it reliable? Is it valid?
The BLUE one always reads the same temperature no matter how hot or cold the water is.
The RED one shows a different temperature every time even if your last measurement was seconds earlier.
The GREEN one seems to read accurately.

What can be said about the reliability and validity of the following? Provide one brief statement for each question (6 responses total).

1. A spelling test with the following item: 2+5=___
   1. Reliability?
   1. Validity?
2. An elastic ruler that stretches to a different length each time it’s used
   1. Reliability?
   1. Validity?
3. A scale that reads 40 pounds at baseline (no weight on the scale)
   1. Reliability?
   1. Validity?

For the following questions, please provide a response that includes an answer to the question followed by an explanation for the answer (2 responses total).

1. Can an instrument be valid if it is not reliable? Explain why or why not.
2. Can an instrument be reliable if it is not valid? Explain why or why not.