A class is testing whether the amount of fertilizer affects bean plant height. One group's setup: Plant 1 gets 0 g of fertilizer and sits in a sunny window; Plant 2 gets 5 g and sits in a shaded corner; Plant 3 gets 10 g and sits under a grow light. Students water each plant whenever they remember. Which revision would MOST improve the validity of this investigation?

Keep light and watering identical for all plants so only fertilizer amount varies

Add a fourth plant that receives 15 g of fertilizer to extend the range tested

Measure plant height every day instead of once a week to collect more data points

Use a different plant species at each fertilizer level to compare their responses

Students must separate a mixture of sand, table salt, and iron filings so that each component is recovered. Which proposed procedure should the teacher approve?

Remove iron with a magnet, add water and filter out the sand, then evaporate the filtrate to recover salt.

Remove iron with a magnet, pour the dry mixture through filter paper, then evaporate the trapped solid.

Add water and filter out the sand, use a magnet on the filtrate to remove iron, then evaporate the water.

Add water and evaporate it off, use a magnet on what remains, then filter the last solids to collect salt.

Voltage (V) Current (A) 3 0.5 6 1.0 9 1.5 A student measures the current through a resistor at several voltages (table). What is the resistance, and what current is predicted at 12 V?

1.5 Ω, and about 8.0 A at 12 V

0.17 Ω, and about 2.0 A at 12 V

A class compares two sites: a forest that burned last summer and a lava flow that recently cooled. A student predicts that both sites will take the same amount of time to become forest again. Which evidence would BEST refute the student's prediction?

The burned site retains soil with seeds and roots, so plants regrow there within months

Both sites lost nearly all of their resident animals during the initial disturbance

The lava flow stays warmer than the burned forest for a short time after it cools

Lichens are found growing on bare rock at the lava flow after many years have passed

A main-sequence star has about 20 times the Sun's mass. Compared with the Sun, which life path is MOST likely for this star?

Much shorter main-sequence life, then a supergiant stage, a supernova, and a neutron star or black hole

Much longer main-sequence life because it has more fuel, then a red giant stage and a white dwarf remnant

About the same main-sequence life, then a supergiant stage that collapses directly into a white dwarf

Much shorter main-sequence life, then a red giant stage, a planetary nebula, and a white dwarf remnant

After a rainstorm, students notice that some puddles on the playground dry up faster than others. Which question would be MOST productive for a student investigation?

How does the surface area of a water sample affect how quickly it evaporates?

What would happen to the school grounds if puddles never dried at all?

Why does water in some places on the playground seem to disappear faster than in others?

Would the playground be better if all of the puddles dried more quickly?

A student heats a green powder in a test tube. The powder turns black, and the gas released turns limewater cloudy, indicating carbon dioxide. Which equation and reaction type BEST match these observations?

CuCO₃ → CuO + CO₂, a decomposition reaction

CuO + CO₂ → CuCO₃, a synthesis reaction

CH₄ + 2O₂ → CO₂ + 2H₂O, a combustion reaction

2Cu + O₂ → 2CuO, a synthesis reaction

A student insists that stepping back from a small wall mirror will let them see more of their own body. Which activity BEST lets students test this claim?

Have the student mark the lowest point of their body they can see from near and far, then compare the two marks

Have the student measure how much smaller their reflection appears from far away, then compare the two image sizes

Have the student compare their view in the wall mirror to their view in a curved mirror of equal size

Have the student trace rays from a lamp to the mirror and measure the angle of reflection at each spot

Five species of warblers eat insects in the same spruce forest. Field observations show that each species feeds mostly in a different part of the tree: the treetop, outer branch tips, inner branches near the trunk, mid-level foliage, or the lower trunk. Which explanation BEST accounts for how these species coexist?

Each species feeds in a different zone, reducing competition for the same insects

The species cooperate by sharing insects equally across the entire spruce tree

One species will soon exclude the others because their niches are identical

Insects are unlimited in spruce forests, so competition between them cannot occur

Fossil species Lived (million years ago) Trilobite 500–470 Brachiopod 480–440 Graptolite 460–420 Crinoid 520–300 The table shows when four fossil species lived. A rock layer in a distant outcrop contains fossils of both the brachiopod and the graptolite. What is the BEST estimate of when this layer formed?

Between 460 and 440 million years ago

Between 480 and 420 million years ago

Between 480 and 460 million years ago

Between 520 and 300 million years ago

Praxis Middle School Science (5442)

Free Praxis Middle Scho 5442 Practice Questions

10 sample questions for the Praxis Middle School Science (5442), with the correct answer and an explanation for each. No account needed. Try each one before you open the answer.

Sections covered on the exam: Nature and Impact of Science and Engineering, Physical Science, Life Science, Earth and Space Science.

Question 1 · Nature and Impact of Science and Engineering
A class is testing whether the amount of fertilizer affects bean plant height. One group's setup: Plant 1 gets 0 g of fertilizer and sits in a sunny window; Plant 2 gets 5 g and sits in a shaded corner; Plant 3 gets 10 g and sits under a grow light. Students water each plant whenever they remember. Which revision would MOST improve the validity of this investigation?
- A.Keep light and watering identical for all plants so only fertilizer amount varies
- B.Add a fourth plant that receives 15 g of fertilizer to extend the range tested
- C.Measure plant height every day instead of once a week to collect more data points
- D.Use a different plant species at each fertilizer level to compare their responses
Show answer and explanation
Answer: A. Keep light and watering identical for all plants so only fertilizer amount varies
Light and water currently change along with fertilizer, so any height difference cannot be attributed to fertilizer alone; holding them constant leaves fertilizer as the only independent variable. Measuring more often or adding another fertilizer level adds data but does nothing to remove the confounding variables, and switching species adds yet another uncontrolled variable.
Question 2 · Physical Science
Students must separate a mixture of sand, table salt, and iron filings so that each component is recovered. Which proposed procedure should the teacher approve?
- A.Remove iron with a magnet, pour the dry mixture through filter paper, then evaporate the trapped solid.
- B.Remove iron with a magnet, add water and filter out the sand, then evaporate the filtrate to recover salt.
- C.Add water and filter out the sand, use a magnet on the filtrate to remove iron, then evaporate the water.
- D.Add water and evaporate it off, use a magnet on what remains, then filter the last solids to collect salt.
Show answer and explanation
Answer: B. Remove iron with a magnet, add water and filter out the sand, then evaporate the filtrate to recover salt.
Iron is magnetic, sand is insoluble, and salt dissolves, so a magnet removes iron, filtration traps sand while dissolved salt passes through, and evaporation recovers the salt. Filtering first would trap the iron with the sand on the paper rather than leaving it in the filtrate. Filtering a dry mixture separates nothing, and evaporating before filtering simply returns the salt to the solid mixture.
Question 3 · Physical Science
Voltage (V) Current (A)
3 0.5
6 1.0
9 1.5
A student measures the current through a resistor at several voltages (table). What is the resistance, and what current is predicted at 12 V?
- A.6 Ω, and about 2.0 A at 12 V
- B.1.5 Ω, and about 8.0 A at 12 V
- C.6 Ω, and about 72 A at 12 V
- D.0.17 Ω, and about 2.0 A at 12 V
Show answer and explanation
Answer: A. 6 Ω, and about 2.0 A at 12 V
By Ohm's law, R = V ÷ I = 3 V ÷ 0.5 A = 6 Ω, the same in every row, so I = 12 V ÷ 6 Ω = 2.0 A. Multiplying voltage by current gives 1.5, which is power in watts, not resistance. Multiplying 12 V by 6 Ω instead of dividing gives the impossible 72 A.
Question 4 · Life Science
A class compares two sites: a forest that burned last summer and a lava flow that recently cooled. A student predicts that both sites will take the same amount of time to become forest again. Which evidence would BEST refute the student's prediction?
- A.Both sites lost nearly all of their resident animals during the initial disturbance
- B.The burned site retains soil with seeds and roots, so plants regrow there within months
- C.The lava flow stays warmer than the burned forest for a short time after it cools
- D.Lichens are found growing on bare rock at the lava flow after many years have passed
Show answer and explanation
Answer: B. The burned site retains soil with seeds and roots, so plants regrow there within months
The burned forest undergoes secondary succession: soil, seed banks, and surviving roots remain, so recovery begins quickly. The lava flow undergoes primary succession and must build soil from bare rock, which takes far longer. Lichens on the lava flow describe primary succession but say nothing about the burned site, and animal loss at both sites does not distinguish the two processes.
Question 5 · Earth and Space Science
A main-sequence star has about 20 times the Sun's mass. Compared with the Sun, which life path is MOST likely for this star?
- A.Much longer main-sequence life because it has more fuel, then a red giant stage and a white dwarf remnant
- B.About the same main-sequence life, then a supergiant stage that collapses directly into a white dwarf
- C.Much shorter main-sequence life, then a red giant stage, a planetary nebula, and a white dwarf remnant
- D.Much shorter main-sequence life, then a supergiant stage, a supernova, and a neutron star or black hole
Show answer and explanation
Answer: D. Much shorter main-sequence life, then a supergiant stage, a supernova, and a neutron star or black hole
A massive star has more fuel but fuses it far faster, so it leaves the main sequence much sooner, swells into a supergiant, and ends in a core-collapse supernova that leaves a neutron star or black hole. The longer-life option assumes more fuel means more time, ignoring the much higher fusion rate. The planetary nebula and white dwarf ending fits Sun-like stars, not one of 20 solar masses.
Question 6 · Nature and Impact of Science and Engineering
After a rainstorm, students notice that some puddles on the playground dry up faster than others. Which question would be MOST productive for a student investigation?
- A.How does the surface area of a water sample affect how quickly it evaporates?
- B.What would happen to the school grounds if puddles never dried at all?
- C.Why does water in some places on the playground seem to disappear faster than in others?
- D.Would the playground be better if all of the puddles dried more quickly?
Show answer and explanation
Answer: A. How does the surface area of a water sample affect how quickly it evaporates?
A productive investigation question names a measurable independent variable (surface area) and a measurable dependent variable (evaporation rate) that students can test with simple materials. The broad "why" question gives no variable to manipulate, the "better" question asks for a value judgment, and the hypothetical question cannot be tested by experiment.
Question 7 · Physical Science
A student heats a green powder in a test tube. The powder turns black, and the gas released turns limewater cloudy, indicating carbon dioxide. Which equation and reaction type BEST match these observations?
- A.CuO + CO₂ → CuCO₃, a synthesis reaction
- B.CuCO₃ → CuO + CO₂, a decomposition reaction
- C.CH₄ + 2O₂ → CO₂ + 2H₂O, a combustion reaction
- D.2Cu + O₂ → 2CuO, a synthesis reaction
Show answer and explanation
Answer: B. CuCO₃ → CuO + CO₂, a decomposition reaction
A single compound breaking into a black solid and a gas is a decomposition reaction, and copper carbonate yielding black copper oxide and carbon dioxide fits every observation. Forming copper oxide from copper metal and oxygen releases no gas, and the reverse synthesis consumes carbon dioxide instead of releasing it. The combustion of methane produces carbon dioxide but involves a gas fuel, not a heated green solid that turns black.
Question 8 · Physical Science
A student insists that stepping back from a small wall mirror will let them see more of their own body. Which activity BEST lets students test this claim?
- A.Have the student measure how much smaller their reflection appears from far away, then compare the two image sizes
- B.Have the student compare their view in the wall mirror to their view in a curved mirror of equal size
- C.Have the student mark the lowest point of their body they can see from near and far, then compare the two marks
- D.Have the student trace rays from a lamp to the mirror and measure the angle of reflection at each spot
Show answer and explanation
Answer: C. Have the student mark the lowest point of their body they can see from near and far, then compare the two marks
In a plane mirror the visible part of the body depends on the mirror's size and height, not on distance, because the image moves back as the person does. Marking the lowest visible point at two distances directly tests the claim, and students find the marks match. Measuring apparent size confuses the angle the image covers with how much of the body is seen.
Question 9 · Life Science
Five species of warblers eat insects in the same spruce forest. Field observations show that each species feeds mostly in a different part of the tree: the treetop, outer branch tips, inner branches near the trunk, mid-level foliage, or the lower trunk. Which explanation BEST accounts for how these species coexist?
- A.The species cooperate by sharing insects equally across the entire spruce tree
- B.Each species feeds in a different zone, reducing competition for the same insects
- C.One species will soon exclude the others because their niches are identical
- D.Insects are unlimited in spruce forests, so competition between them cannot occur
Show answer and explanation
Answer: B. Each species feeds in a different zone, reducing competition for the same insects
Using different parts of the tree is resource partitioning, which divides a shared resource so each species occupies a distinct niche and competition is reduced. Competitive exclusion would occur only if the niches were identical, but the observed feeding zones show the niches differ.
Question 10 · Earth and Space Science
Fossil species Lived (million years ago)
Trilobite 500–470
Brachiopod 480–440
Graptolite 460–420
Crinoid 520–300
The table shows when four fossil species lived. A rock layer in a distant outcrop contains fossils of both the brachiopod and the graptolite. What is the BEST estimate of when this layer formed?
- A.Between 480 and 420 million years ago
- B.Between 460 and 440 million years ago
- C.Between 480 and 460 million years ago
- D.Between 520 and 300 million years ago
Show answer and explanation
Answer: B. Between 460 and 440 million years ago
The two species lived together only where their ranges overlap: the brachiopod from 480 to 440 and the graptolite from 460 to 420, giving 460 to 440 million years ago. The 480 to 420 range combines the two ranges instead of overlapping them. The crinoid's long range, 520 to 300, is why it is a poor index fossil and cannot narrow the age.

Voltage (V)	Current (A)
3	0.5
6	1.0
9	1.5

Fossil species	Lived (million years ago)
Trilobite	500–470
Brachiopod	480–440
Graptolite	460–420
Crinoid	520–300

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