1) Rinse the flask with tap water. 2) Pour in 100 mL of pond water. 3) Set the flask on the balance and record the mass. 4) Heat the flask for 10 minutes. Why is the mass recorded before the flask is heated?

1) Set the ice bath on the table. 2) Lower the thermometer until the bulb is covered. 3) Wait 3 minutes without touching the glass. 4) Read the temperature at eye level. Why must the glass not be touched during the three minutes?

1) Set the dial to DC volts. 2) Touch the black probe to the negative terminal. 3) Touch the red probe to the positive terminal. 4) Read the display and record the value. The reading comes out with a minus sign. Which mistake explains that?

1) Hang the string from the clamp. 2) Pull the bob 10 cm to one side. 3) Release the bob without pushing it. 4) Time ten full swings, then divide by ten. Why time ten swings and divide, rather than time a single swing?

1) Empty the rain gauge on Monday morning. 2) Leave it upright in the open yard. 3) On Friday, read the water level at eye level. 4) Divide that reading by five. Someone empties the gauge on Wednesday. What does Friday no longer give?

1) Spread the dried soil on a tray. 2) Pour it through the coarse sieve. 3) Weigh what stays on top of the sieve. 4) Weigh what falls through into the pan. What do the two weighings together let you work out?

1) Wipe extra paint onto newspaper. 2) Rinse the brush under warm water. 3) Work soap through the bristles. 4) Reshape the tip and lay the brush flat to dry. A student dries the brush bristles-down. Which step is defeated?

1) Click the lowest-power lens into place. 2) Put the slide on the stage under the clips. 3) Turn the coarse knob until the image is nearly sharp. 4) Finish with the fine knob. Why is the coarse knob used before the fine knob?

1) Mix the flour, water, and yeast. 2) Knead the dough for 8 minutes. 3) Cover the bowl and keep it at 30 degrees Celsius for one hour. 4) Punch the dough down. Why is the bowl covered for the hour?

1) Wipe the print bed with alcohol. 2) Slide a sheet of paper under the nozzle. 3) Raise the bed until the paper drags slightly. 4) Repeat at all four corners. Why is the same adjustment repeated at all four corners?

1) Label three cups A, B, and C. 2) Fill each cup with 250 mL of water. 3) Add one tablet to cup B only. 4) Record the water temperature in all three cups. What must be done before the tablet is added?

1) Fold the filter paper into a cone. 2) Set the cone in the funnel and wet it. 3) Place the funnel over the empty jar. 4) Pour the muddy water into the funnel. What must be done before the muddy water is poured?

1) Rinse the test tube with distilled water. 2) Fill it to the 10 mL line with tap water. 3) Add soap one drop at a time, shaking after each drop. 4) Stop when the suds last 30 seconds. What must happen before the first drop of soap?

1) Put on gloves. 2) Rinse the sample bottle in the stream. 3) Fill the bottle facing upstream. 4) Cap it and write the time on the tag. What must be done before the bottle is filled?

1) Connect the battery holder to the switch. 2) Connect the switch to the bulb. 3) Connect the bulb back to the battery holder. 4) Close the switch and watch the bulb. What must be true before the switch is closed?

1) Sand the shelf smooth. 2) Wipe off the dust with a damp cloth. 3) Brush on a coat of primer. 4) Let the primer dry 4 hours, then paint. What must be done before the primer is brushed on?

1) Line each cup with a damp paper towel. 2) Press four bean seeds against the side of each cup. 3) Set one cup in the dark and one on the windowsill. 4) Add water when the towel looks dry. What must be done before the seeds go in?

1) Line the box with foil, shiny side out. 2) Tape clear plastic over the opening. 3) Set the box in full sun for 30 minutes. 4) Read the inside thermometer. What must be done before the box goes into the sun?

1) Charge the flashlight for 2 hours. 2) Write down the start time. 3) Switch it on and leave it running. 4) Write down the time the beam dies. What must be done before the flashlight is switched on?

1) Turn off the power switch. 2) Unclip the old battery. 3) Snap in the new battery. 4) Turn the power switch back on. What goes wrong if Steps 1 and 2 are swapped?

1) Plug in the hot glue gun. 2) Wait 5 minutes for it to heat. 3) Squeeze the trigger to lay a bead. 4) Unplug it and let it cool. What goes wrong if Steps 2 and 3 are swapped?

1) Loosen the lug nuts a half turn. 2) Jack up the car. 3) Take the lug nuts and wheel off. 4) Lower the car. What goes wrong if Steps 1 and 2 are swapped?

1) Unplug the blender. 2) Lift out the blade unit. 3) Wash the blade unit in soapy water. 4) Plug the blender back in. What goes wrong if Steps 1 and 2 are swapped?

1) Slide the memory card in until it clicks. 2) Turn the camera on. 3) Take the photo. 4) Turn the camera off, then pull the card out. What goes wrong if Steps 3 and 4 are swapped?

1) Rinse the dry beans. 2) Soak them overnight in cold water. 3) Drain them. 4) Boil them for 45 minutes. What goes wrong if Steps 2 and 3 are swapped?

1) Clamp the board to the bench. 2) Mark the cut line in pencil. 3) Saw along the line. 4) Sand the cut edge. What goes wrong if Steps 2 and 3 are swapped?

1) Shake the closed paint can for one minute. 2) Pry off the lid. 3) Stir the paint with a stick. 4) Pour the paint into the tray. What goes wrong if Steps 1 and 2 are swapped?

1) Cut a strip of paper 15 cm long. 2) Dip one end 1 cm into the ink. 3) Wait 5 minutes. 4) Measure how far the ink traveled up the strip. What goes wrong if the strip is dipped 5 cm into the ink instead?

1) Cut two boards, each 45 cm long. 2) Drill a pilot hole 2 cm from each end. 3) Drive a 5 cm screw into each hole. 4) Check the corner with a square. Why is a hole drilled before the screw goes in?

1) Fill the graduated cup to the 100 mL line. 2) Slide the rock in gently. 3) Read the new water line. 4) Subtract 100 from that reading. How much water does the procedure start with?

1) Fill the pot with water at 20 degrees Celsius. 2) Clip the thermometer to the side. 3) Heat until the water reads 80 degrees Celsius. 4) Start the timer and stop it at 95 degrees Celsius. Which temperature does the procedure reach before timing starts?

1) Chalk a 10-meter lane on the sidewalk. 2) Start the stopwatch as the cart crosses the first mark. 3) Stop it at the second mark. 4) Divide 10 by the seconds recorded. Which distance does the procedure use?

1) Pour 150 mL of vinegar into the jar. 2) Add 5 mL of baking soda. 3) Cap the jar loosely. 4) Record the highest foam level. How much baking soda does the procedure call for?

1) Hang the spring from the hook. 2) Measure its length in centimeters. 3) Hang a 200-gram weight from it. 4) Measure the length again and subtract the first reading. A student skips the first measurement. What cannot be worked out?

A lab sheet's key says a bold dot marks a step to repeat. 1) Add one drop of indicator. 2) [dot] Swirl and check the color. 3) Record the color once it stops changing. When should the student move on to Step 3?

In this manual, to seat a part means to press it in until it clicks. 1) Line the filter up with the slot. 2) Seat the filter. 3) Close the lid. What goes wrong if the lid is closed before the filter clicks?

In this guide, a step printed in italics is done only if the first try fails. 1) Press start. 2) Wait for the green light. 3) Unplug the unit, wait 10 seconds, and press start again. Step 3 is in italics. What does that mean?

1) Weigh the empty dish. 2) Add 50 mL of salt water. 3) Leave it under a lamp until the water is gone. 4) Weigh the dish again. What is the point of the whole procedure?

A recipe reads: 1) Heat the oven to 180 degrees Celsius. 2) Grease the pan. 3) Pour in the batter. 4) Bake for 25 minutes. True or False: the recipe has the pan greased before the batter is poured.

A manual reads: 1) Turn off the water valve. 2) Loosen the nut. 3) Pull out the old hose. 4) Attach the new hose. True or False: the manual has the nut loosened before the water valve is turned off.