Challenge
Time: to measure or record the speed, duration, or rate of something. That is just one definition of the word, and there are many others. But this is the most accurate definition that will be needed for this month’s STEM challenge. There are many ways to measure time and the challenge will test different ways to measure time in seconds. What are the different ways to measure time? How many measurements can you think of that involve some kind of time? How much time does it take to do different tasks? Answering these questions could help you design a timer, which is the STEM Challenge. Your timer though is going to be manual and not electronic! What items can you use to build a timer? How will you test it to know it measures the time you want it to? Do you need a timer to measure your timer? Your goal is to build a timer using some kind of block or item that can be knocked over like dominoes. The timer must go for almost exactly 5 or 10 seconds.

​Your timer does have some criteria and constraints. The timer starts from when the first item gets pushed over to when the last item falls. Only items being knocked over can be used in the creation. You can mix and match different items to create the domino effect.  

Materials

• stopwatch or timer
• blocks
• dominoes
• books
• Legos
• markers

Hints and Tips for Success

1. Allow students planning and discussion time by having them experiment with the items to see how fast/slow they fall over and by changing the distance between them.
2. After experimenting, allow student groups to plan their timer by drawing it out and labeling their materials being used. Include predictions for how many items they think they will need for the designated time.
3. For differentiation, add additional materials to use, change the time needed to be timed, show different ways to set up the domino items. Adjustments could be made to make it more challenging or simpler.
4. Make sure to standardize the timer as in when the stopwatch/timer starts to measure how long the creation lasts. If needed, have this person be consistent for each group working on the problem.

Challenge
Did you know in August there are two separate special days dedicated to marshmallows? One day is August 10, which is National S’mores Day, and you can’t have a s’more without a marshmallow! The other day is August 30, which is Toasted Marshmallow Day! So of course, this month’s challenge has to do with marshmallows, especially toasting them AND making s’mores! Your challenge is to create a contraption that will make a marshmallow warm and soft along with chocolate to make a s’mores. You probably will not be able to really toast it since fire will not be used. You’ll be using the sun’s heat energy to help you accomplish the task. What materials will work best to capture the heat?  How large should the contraption be?  What shape, size, and design should it be to be most effective? How can you measure the effectiveness of the contraption?

Your contraption and creation do have some criteria and constraints. Each contraption or solar oven should test one marshmallow or piece of chocolate at a time. All the marshmallows and chocolate should be about the same size and type. While testing, the solar ovens should be placed in the same sunny area. Use the same thermometer for taking the temperature inside the box.

Materials

• aluminum foil
• carboard boxes
• clear material (plastic wrap, transparencies, etc.)
• felt or other fabric
• containers/plates for setting food items
• shiny paper
• rocks
• mirrors
• tape
• marshmallows
• graham crackers
• chocolate bars
• thermometer
• stopwatch
• any other items needed

Hints and Tips for Success

1. Allow students planning and discussion time by having them experiment with the items to see how flexible, movable, and heavy they are. Also, let students experiment for how hot objects get under light or outside.
2. After experimenting, allow student groups to plan their design by drawing it out and labeling their materials being used. Include as many ways to improve their ovens as needed. You may want to help students with a design by suggesting a window on top of their ovens to be able to see what’s happening inside.
3. For differentiation, adjust the amount of materials available and allowed to use, add any additional materials, take away certain materials, show them different solar oven examples, extend/lessen the time of cooking, try different sizes of marshmallows or chocolate. Adjustments could be made to make it more challenging or simpler.
4. Make sure to standardize the dimensions of the marshmallow or chocolate. Remind students to take heat measurements with the thermometers periodically throughout “toasting” the marshmallows.

Connect to science by discussing heat energy, properties of materials which work best for the solar oven, energy transformations, solar

Challenge
With recent launches of rockets and a few more happening in July, it's time to blastoff this month with the STEM Challenge!  Check out the Events Calendar at Kennedy Space Center for upcoming launches to watch them live or previous launches to prepare for builidng your own rocket to launch. Your challenge is to create and design a rocket and launch pad for blastoff. Adjust the rocket fuel and rocket design to see which provides the best blastoff. What size rocket will work best? What if the rocket had fins or other designs? Does the ratio of fuel ingredients matter? What about the ratio of fuel to the rocket size? What should the rocket launch pad be? The goal is create the best rocket you can and to experiment with all those questions!

Design some sort of launch pad first. The goal of the launch pad is to hold the bottle upside down in an upright position. Next, decide on a plastic bottle to use as your rocket and design your rocket. Finally, experiment with the ratio of your rocket fuel or baking soda and vinegar. 

Your creation does have some criteria and constraints. Make sure safety is noted at all times. After the rocket is fueled, place it in the launch pad, and back away. Only launch rockets in a wide open spaces and from the designed launch pad. For launching, fill the bottle with the chosen vinegar ratio, pour the baking soda on a 4"x4" piece of paper towel, wrap up the baking soda with the paper towel, stuff it carefully into the spout of the bottle, cork the bottle, and turn it upside down into the launcher and move quickly out of the way. Prepare for blastoff!

Materials

• various plastic bottles
• corks or foam for bottle toppers
• vinegar
• baking soda
• paper towels
• measuring cups/spoons
• rocket decorations
• launch pad materials: Legos, craft sticks, glue, tape, blocks, etc.

​
Hints and Tips for Success

1. Allow students planning and discussion time by having them decide which type of bottle to use so they can start building their launch pad.
2. Test to see if the launch pad is sturdy and will hold the bottle with liquid. Add water to the bottle with a cap to do this test. 
   
3. Plan out the ratio of baking soda and vinegar. As a guide, a 2 liter bottle does well with 1-2 cups of vinegar and a tablespoon of baking soda. Have students experiment with different amounts to see which they think is best. 
4. Always ensure safety when loading and launching the rockets. 
5. Record the launches in a constant spot so students can compare heights and launches if wanted. 
6. Connect to math by discussing ratios, measurement, conversions, etc. 
7. Connect to science by discussing engineering, properties of matter, solids, liquids, gases, pressure, chemical reactions, etc. 

Challenge
Looking for something to do inside or outside? Why not start a garden? You could choose to plant flowers, vegetables, or different kinds of plants. You can find vegetable seeds almost in any vegetable in your house. The beginning of May is the perfect time to start planting! Find those seeds and plant them in a pot with some soil. Your challenge this week has to deal with planting. How will they grow best? What do they need? How much of that do they need? Can you create some kind of experiment, tracking the data, to find out? Try it with multiple seeds, different kinds of plants, different amounts or kinds of soil, different places outside or inside (shady or sunny), different amounts of water, or anything else you can think of to experiment.

Your experiment does have some criteria and constraints. Make sure to collect data on your plants. Before beginning make a hypothesis about which will grow the best and why. After completing the experiment, make a claim about how to grow the plant best by using evidence and reasoning.

Materials

• various vegetable seeds
• various soils (sand, potting soil, dirt, etc.)
• data tools (notebook, ruler, scale, etc.)
• pots or containers for planting

​
Hints and Tips for Success

1. Use empty egg cartons to start out the seeds. Place one seed in each holder. These can easily be cut apart too for different sections. The different sections could represent either different seeds or the different experiment types.
2. Make sure to do multiple examples of the same experiment. Plant 3-4 seeds the same way to ensure fair trials.
3. Collect data the same way for each plant by measuring, weighing (if possible), when the plant is placed, and recording the amount of water added.
4. Be patient!

Challenge
Are you stuck at home and looking for something fun, easy, and science to do? I’m a big fan of Rube Goldberg machines and think this might be something to tie fun, easy, and science all together!
What is a Rube Goldberg machine though? Let’s start with Rube Goldberg, himself. He was an American Pulitzer Prize winning cartoonist, sculptor, author, engineer, and inventor, and his work is a classic example of the melding of art and science. Goldberg began his career as an engineer, and later became a cartoonist who drew elaborate illustrations of contraptions made up of pulleys, cups, birds, balloons, and watering cans that were designed to solve a simple task such as opening a window or setting an alarm clock. Interestingly, Goldberg only drew the pictures, and never built any of his inventions. However, these pictures have since served as inspiration for makers and builders who want the challenge of making wild inventions to solve everyday problems. 
So, that is your challenge for today. Can you build a Rube Goldberg machine to solve a simple problem? Maybe you want to turn on a fan, pour a glass of water, knock over an item, catch something, turn on a light, pop a balloon, ring a bell etc.! The possibilities are endless.

For this challenge, there is no criteria or constraints. Use your creativity, ideas, thinking, and materials to create your own contraption!

Materials

• anything at home will work, but here are some useful/common items
• dominoes
• craft sticks
• toy cars
• wooden blocks
• car tracks
• any type of balls
• string
• tape
• cardboard tubes
• cups

Hints and Tips for Success

1. Watch some Rube Goldberg videos to get inspired and imagine the possibilities. OK Go is notorious for their amazingly-complicated designs.  https://youtu.be/qybUFnY7Y8w
2. Decide which problem you would like to solve. Sample problems are listed above but don't limit yourself!
3. Gather your supplies and lay them out so they're easily seen. Start with the basics and then search your home for more supplies as you start to tinker. This list might help you find helpful items https://tinkerlab.com/wp-content/uploads/2015/03/Rube-Goldberg-Activity-List.pdf
4. Start building your machine! Experiment with the basic ideas of the chain reaction. Anything that tips something else over (and so on)!
5. Build one part at a time and keep adding on.
6. Do not be afraid of failure! As you test and try out different set-ups, you will probably fail a few times. But, this is great news! Failure is an excellent piece of the invention process. Without mistakes, you won't learn so celebrate it as part of the learning process!

Challenge
NCAA March Madness is a single-elimination basketball tournament played each spring. 68 Division I college basketball teams battle for the national championship. It’s “Madness” because it captures the excitement around sports with the tournament, the upsets that happen between teams, the filling out of brackets, and the teams vying for the top spot! Since the tournament happens mostly in March, it is going to be the theme for this month’s STEM Challenge. Your challenge is to create a “trophy” for the champions of the basketball tournament. Your trophy must hold an actual basketball at the top of the trophy. What shape, size, and design should the trophy be to hold the basketball? How tall should the trophy be? What materials can you use?
Your creation does have some criteria and constraints. As mentioned, the basketball has to sit at the top of the trophy. It should support the basketball for 20 seconds without crumpling. The basketball cannot be taped to the supports. The supports cannot be taped to the building surface. It must be at least 12 inches high. You can only use the materials given.

Materials

• basketball
• newspapers
• masking tape

​
Hints and Tips for Success

1. Allow students planning and discussion time by having them experiment with the newspaper to see the different ways they can build with it.
2. After experimenting, allow student groups to plan their design by drawing it out and labeling where they will put the tape (each group should get 1 roll of tape). Include as many ways to improve their trophies as needed.
3. For differentiation, adjust the amount of materials available and allowed to use, add any additional materials, take away certain materials, show them different ways to manipulate the newspaper, change the required height. Adjustments could be made to make it more challenging or simpler.
4. Make sure student groups aren’t relying heavily on tape. It is meant to hold the newspaper together and not for supports.
5. Connect to math by discussing dimensions and what that means, measurement, shapes, symmetry, angles, etc.
6. Connect to science by discussing engineering, structure and function, balance and unbalanced forces, etc. 

Challenge
February is Cupid’s month and who is Cupid without his bow and arrow he uses to help people fall in love? But Cupid is experiencing some trouble with his arrows. They seem to be going too slow to reach his designated targets. He needs your help to make Valentine’s Day a success. This is your challenge to design an arrow protocol that is speedier than Cupid’s current arrows. Since you will be making a protocol arrow by representing an object, think about the materials being used. What types of balloons will make the best arrow? Are different shapes better than others? How can the materials be manipulated for best use? How can you make the arrow look like an arrow and be aerodynamic?

Your arrow creation does have some criteria and constraints. You can only use one balloon in your design. The finished product has to resemble an arrow Cupid would use by using the construction paper as design aspects. It has to be placed on the straw line system to be tested. It has to travel about 10' and hit the target to stop the time trial. Finally, the speedier, the better.

Materials

• various types of tape (scotch, masking, packing, duct, etc.)
• scissors
• straws
• various types of balloons
• binder clips
• construction paper
• string

Hints and Tips for Success

1. Set up the “shooting range” straw line. Insert about 12’ of string through a straw. Place two chairs (or similar tall objects) about 10 feet from each other. Tie the string onto the back of each chair so it is taut. The straw should easily glide along the string and be far enough off the ground so balloons can glide along it as well when attached. Place some kind of paper target (heart) at one end to indicate the stopping point of the timer. Set up multiple straw lines if wanted to test more arrows concurrently.
2. Make sure to standardize the starting point of the straw each time. If needed, draw a line on the string for where the straw has to start. Students could choose where they attach their arrow on the straw as long as the straw starts in the proper place.
3. Discuss with process with students for how they will blow up their balloon, place the binder clip on their balloon to not let air out, design their arrow, attach it how they would like to the straw for it to glide along the string, remove the binder clip, start the timer, and stop it when the arrow hits the target.
4. Allow students planning and discussion time by having them experiment with the balloons to see what shapes they become and how fast they release air.
5. After experimenting, allow student groups to plan their design by drawing it out and labeling their materials being used. Include as many ways to improve their balloon arrows as needed.
6. For differentiation, adjust the amount of materials available and allowed to use, add any additional materials, take away certain materials, adjust the length of the shooting range, show examples of how it works. Adjustments could be made to make it more challenging or simpler.
7. Connect to science by discussing Newton’s Third Law, force, properties of matter, aerodynamics, pressure, etc.
8. Connect to social studies or ELA by researching Cupid in his different mythologies and current adaptations.

​Challenge
January is a great time to have a snowball fight. Every good snowball fight needs some kind of fort for protection and to build more snowballs under cover. Snowball fights are best suited for outdoors, but what about modeling one inside? This will be part of your challenge, building a fort to withstand attacks from snowballs. Since you will be modeling the activity, representing an idea, object, a system or process, think of the materials being used. What kind of structure makes the best fort? Are different shapes better than others? How can the materials be manipulated for best use?
​
Your snowball fort creation does have some criteria and constraints. The fort is being constructed out of 100 index cards and only 12 inches of tape. The fort has to be at least 9 inches tall and 10 inches long. To test the fort, determine how 3 snowballs (cotton balls or wadded up pieces of paper) can be fairly launched at the fort to test its durability.

Materials

• index cards
• cotton balls
• tape
• rulers
• paper
• scissors

Hints and Tips for Success

1. Allow students planning and discussion time by having them experiment with the index cards to see how flexible and durable they are.
2. After experimenting, allow student groups to plan their design by drawing it out and doing a little testing with a few cards. Include as many ways to improve their forts as needed.
3. For differentiation, adjust the amount of materials available and allowed to use, add any additional materials, take away certain materials, include different amounts of snowballs launched, change the dimensions of the fort, etc. Adjustments could be made to make it more challenging or simpler.
4. Make sure to standardize the launching of the snowballs so all forts experience similar attacks. Also, standardize the snowballs if using paper to make sure they are about the same size.
5. Connect to math by discussing dimensions and what that means, measurement, shapes, symmetry, angles, etc.
6. Connect to social studies by researching the different kinds of forts, how they were used, the different materials used to build them, where there still are forts, etc.

Challenge
This is the time of year when we often start noticing more spiders and their webs. We tend to associate spiders and webs with Halloween. Why? Well, many spiders reach adulthood in the late summer and early fall. So, they become more visible to us, and there are more spiders to create even more webs. Spider silk, the strongest fiber in nature, is used to make their webs. It is stronger than steel and thinner than a strand of hair! Webs are used to help spiders catch their prey and to help alert the spider of predators. If you haven’t guessed it by now, this month’s challenge has to deal with spider webs. Your challenge is to create a spider web to capture the most items. What material would work best for capturing the items? What shape, size, and design should the web be to be most effective? Can you emulate an actual spider’s web from nature?
Your spider web creation does have some criteria and constraints. Determine specific dimensions for your webs so they turn out to be generally the same size. The web must look like a spider web, meaning with strands and holes. The objects being caught in the web must be the same with identical processes of how the objects reach the webs.

Materials

• various types of tape (scotch, masking, packing, duct, etc.)
• various types of string (thick, thin, yarn, thread, fishing, kite, etc.)
• scissors
• paper clips
• straws
• Velcro
• various cups
• objects to catch in web (plastic spider rings, Styrofoam peanuts, pom poms, connecting cubes, bits of paper, etc.)
• any other additional materials

Hints and Tips for Success

1. Allow students planning and discussion time by having them experiment with the items to see how flexible, movable, and heavy they are. Also, let students experiment with the objects they are catching in their webs.
2. After experimenting, allow student groups to plan their design by drawing it out and labeling their materials being used. Include as many ways to improve their webs as needed.
3. For differentiation, adjust the amount of materials available and allowed to use, add any additional materials, take away certain materials, show them different kinds of spider webs, challenge them to collect a certain number of objects or more, change the dimensions or shape of the web, use different objects to catch. Adjustments could be made to make it more challenging or simpler.
4. Make sure to standardize the dimensions of the web so testing can be fair for all creations. Also, standardize how the objects will be reaching the webs. Will groups hold their webs up in one place and throw the objects at the web from another? Will the web be held horizontally or vertically? Will they be tossed one at a time or all at the same time? Will the students develop some kind of launcher so tosses are all the same? OR will the students think of something completely different?
5. Connect to math by discussing dimensions and what that means, measurement, shapes, symmetry, translations, angles, etc.
6. Connect to science by discussing predator, prey, survival behavior, food chains/webs, habitats, structure and function of spiders, how humans mimic organisms, etc.
7. Connect to ELA by researching the different kinds of spiders, the webs they weave, and why they weave them that way and/or by reading The Very Busy Spider by Eric Carle, Spiders by Aaron Carr, Spiders and Their Webs by Linda Taglianferro, Weaving Wonders by Nancy Loewen, Spinning Spiders by Melvin Berger or National Geographic Readers: Spiders by Laura Marsh to explore different kinds of spiders, spider facts, and more about spider webs. 

Challenge
Arrrrrre you aware that September 19th is International Talk Like a Pirate Day? Get ye mateys aboard for this month’s challenge, which is pirate themed. Treasure maps were popular among the crew to look for their booty. They included symbols, directions, pictures, booby traps, keys, and other forms of communication to help remember where their treasure was hidden. Your challenge this month is to create a treasure map to locate a certain place or object. It focuses on the engineering practice of generating and comparing multiple possible solutions to a problem based on how well each is likely to meet the criteria of the problem. What kind of map will be best? What should be included on a map? How can the communication be clear and directions easy to follow?
 
Your treasure map does have some criteria and constraints. Make sure all groups are creating a treasure map to the same place and starting from the same location. This way groups will be able to compare their solutions. A rubric or system of comparing should be devised to regulate map comparisons. Rubric components could include ease of reading map, ability to find the treasure according to the map, design, or type of directions.

Materials

• various large, colors and sizes of paper
• markers
• pens
• pencils

Hints and Tips for Success

1. Allow students planning, discussion, and research time to decide how they would like to set up their maps, what symbols to use, and how they will communicate their directions on the map.
2. After research, allow student groups to plan and create their final design. Include as many ways to improve their maps as needed.
3. For differentiation, adjust the amount of materials available and allowed to use, add any additional materials, show students map examples, start with an easy map/location, include multiple stops or treasure items. Adjustments could be made to make it more challenging or simpler.
4. Make sure to standardize the locations students have to start and stop at. If needed, secretly provide different locations students need to map so students are not all going to the same place.
5. Discuss pros and cons of map making.
6. Connect to social studies by discussing map keys, cartography, map scale, pirate history, directions, compass rose, etc.
7. Connect to art by discussing scale, proportion, quantity, distance, viewpoint, etc.
8. Connect to math by discussing the coordinate grid system, measurement, conversions, etc. 

Challenge
Summer is nearing an end but there is still time to build a sandcastle! The good news is you don't even need to go to the beach to do so. The beach experiences way too much erosion by wind and rain anyway to keep a sandcastle around for multiple days. Can you think of other ways erosion affects the land or other things? What does all this have to do with this month's challenge? This month, your challenge is to engineer sand so it can withstand the erosion elements of wind and water. You're going to test out different recipes to determine which sand would be best to keep a sandcastle in tact during a windy day or a wet one. What ingredients might we need to do so? How much of each ingredient? How can we test out a recipe before building an entire sandcastle? 

Your sand recipe does have some criteria and constraints. Only the materials provided can be used in your recipe. The same kind of sand should be used when performing tests against each other. Other sands can be used as long as all groups have access to the same sand. Try to change only one variable at a time so fair tests can be done. Use a Dixie cup as the standard size of a brick to measure the effects of erosion.

*This idea and challenge can be further explored in the Advancing STEM Grade 4 Unit, Centuries of Change: Processes That Shape the Earth. 

Materials

• sand
• liquid white glue
• Dixie cups
• non-stick spray
• water
• watering can (shower head spout)
• small fan
• plastic spoons
• mixing bowls

Hints and Tips for Success

1. Provide sample castles for students to improve. These will act as a baseline and starting point for them. Mix together 1 Dixie cup of sand and 3 teaspoons of water. Spray the inside of the Dixie cup with the non-stick spray. Pack the mixture into the cup and let sit. Pack another cup with sand but without mixing in the water. 
2. Turnover the cups to expose the small sand castles. You might have to tear the cup off of the sand. Share the recipes for those two mixtures with the students. Allow the fan to blow on each. Dump about 1 cup of water on each with the watering can. Collect and discuss the data and evidence of each test. Charge students with the challenge.
3. Allow students planning and discussion time by having them experiment with the items to see how they mix together. Students could conduct mini experiments by placing small amounts of the mixing items together to see how they interact in very small doses.
4. After experimenting, allow student groups to plan their recipe of what will go in 1 Dixie cup. Include as many ways to improve their sand castle recipes as needed. 
5. For differentiation, adjust the amount of materials available and allowed to use (limit the amout of glue allowed to be added), add any additional materials, take away certain materials, show them different versions others have created, use different sized cups, use different types of sand. Adjustments could be made to make it more challenging or simpler.
6. Make sure to always standardize their tests when collecting results such as distance fan is from the sandcastle, speed of the fan, amount of water being poured on it, how high the spout is above the sandcastle, ways of collecting data and evidence.
7. Connect to mathematics by discussing measurement, ratios, conversions, etc.
8. Connect to science by discussing erosion, weathering, natural disasters, human preparation for events such as natural disasters, mixtures, solutions, matter, etc.

Challenge
The days from July 3 to August 11 are known as the Dog Days of Summer, usually the hottest, muggiest of the year. This is the period when Sirius, the Dog Star, rises at the same time as the Sun. The ancient Romans defined this period and believed the weather was warmer because Sirius was also providing heat for the Earth, hence Dog Days of Summer. So, how can this heat help us with this month’s STEM challenge? Heat rises which is going to be a good fact to know when building your solar updraft tower, which harnesses the Sun’s heat energy to do work. Our version to going to use empty cylinders with a pinwheel attached to the top. The goal is to get the pinwheel to rotate from the heat rising through the solar tower. What materials would be best to use for the tower sections? Do certain items warm up faster or more than others? How can the pinwheel be attached so it can spin freely? How high off the ground should your updraft tower be? Your challenge is to create an updraft tower that uses the Sun’s heat energy to spin the pinwheel the most amount of times. Updraft Tower Example.

Your updraft tower does have some criteria and constraints. Only the materials provided can be used in your design. The tower needs to be at least 1 foot tall. Every group should build and construct the same type of pinwheel for fair testing during the rotations.
 
*This idea and challenge can be further explored in the Advancing STEM Grade 4 Unit, Full of Potential: The Effects of Energy.

Materials

• aluminum cans (various sizes without tops and bottoms)
• can opener
• cardboard tubes (various sizes)
• plastic cylinder containers (various sizes)
• different colored duct tape
• clear tape
• paper clips (for attaching the pinwheel)
• paper for pinwheel
• simple pinwheel template

​
Hints and Tips for Success

1. Allow students planning and discussion time by having them experiment with the items to see how flexible, movable, and heavy they are. Students could conduct mini experiments by placing different items in the heat to see which warm up the fastest or are the warmest by the end of a set time period. Students could also experiment with different sized pinwheels and the type of paper used to make them to see which spins easiest or the best.
2. After experimenting, allow student groups to plan their design. Include as many ways to improve their updraft towers as needed.
3. For differentiation, adjust the amount of materials available and allowed to use, add any additional materials, take away certain materials, show them different versions others have created, help determine how to attach the pinwheel or how to raise the bottom so air may enter. Adjustments could be made to make it more challenging or simpler.
4. Make sure to standardize the pinwheel students are using and the area they are placing their towers. Or, the latter could be part of their experiment/challenge. Additionally, how high the towers are placed off the ground could impact how well it works. This could also be standardized.
5. Connect to science by discussing solar power/energy, renewable/non-renewable energy, convection, weather patterns, energy, work, etc.