For more activities, check out our Activity of the Month page

Outdoor STEM @ Home: Simple Orienteering Course

This activity combines a valuable outdoor skill with using math in a fun way to create a scavenger hunt/geocache style course. All you need is:

  • tape measure
  • pencil
  • something to write on or in
  • compass (you can use a compass app on a smartphone)
  • small tokens and/or lots of objects like trees or bushes outside

This activity is good for students in grades 3+ or who have the ability to convert one measurement to another (such as feet to inches and inches to feet). 

Part 1: Distance

In order to set up the course (and to solve a course) you’ll need to know your pace measurement. A pace is equal to two steps. Alternatively, it may be easier for some students to count steps rather than paces, even if it’s a higher number; use your best judgement. To find out your pace or step measurement:

  1. Lay out 20′ of the tape measure.
  2. Start at one end, and walk normally towards the other end, counting your paces (or steps).
  3. Do this several times
  4. Calculate the average/mean (older kids) or mode (the most common number, for younger kids)
  5. Divide that number by two, so that you know how many of your paces/steps cover 10 feet
  6. Remember this number! 

Part 2: Angles/Compass

This is a great opportunity to teach your kids North, South, East and West if they don’t know it. There are two main points to learn here:

  1. North stays the same, and the arrow will always point to North
  2. Holding the compass flat and always pointing away from you, whichever direction you turn will give you your angle (with one extra step if you’re using an actual compass)

While creating the course, the compass is needed to to know which direction you’re heading. To get this number (always between 0-360 degrees), pick an object in the distance and face it holding your compass flat, (then if using an actual compass, you need to turn the dial to put the N by the red arrow), then read the number that is at the top of your compass. For example, if you happen to face exactly East, your number should be 90 degrees. If these directions for reading the compass are still confusing, check out this explanation. *Note: for simplicity, ignore teaching declination for this activity. 

Part 3: Creating the Course

This is the fun part! Pick a starting point, and then pick a random object/point in the distance (reasonable distance!). Take a bearing/angle, then pace the distance towards that area. Write down the angle and distance in feet (you’ll need to convert from paces or steps). Leave a token or mark this object. Repeat this several times until your have up to 10 objects in the course. 

Ideally, there will be another person or team of people creating a different course at the same time, and then you can swap courses and try to solve the other person’s course. To solve a course, simply reverse the steps. From the starting point, turn the dial to put the angle at the top of the compass, then turn yourself to get the N on the red arrow. Then convert the distance to your paces, and walk that many paces forward. Look for the token to confirm you have the right object. Then continue repeating those steps until you complete the course. It’s important to remember that the longer the distance, the more off course you can get even with a small degree different. 

Enjoy; email if you have any questions! 

Household Science: Deep Dive into the Baking Soda and Vinegar Reaction

Vinegar + Baking Soda: who hasn’t had fun with this reaction? If I were to ask what happens when baking soda combines with vinegar, most people would be able to answer with some variety of “fizz”, “bubbles”, “a mess”, etc. It’s the basis of the well known and loved science fair volcano. But there’s three extra things you can do with this set-up of the reaction besides just ooh and ahh over the fun reaction, still using materials you likely already have on hand. If you do this activity, don’t forget to take some fun pictures! Feel free to share them using our social media hashtag, #MakingSTEAMsustainable. 

For your basic setup, you’ll need:

  • Baking Soda (~2 Tbs)
  • Vinegar (~1/2 c)
  • Balloon
  • Narrow-ish mouthed bottle (a glass bottle works best)
  • Spoon
  • Optional but helpful: funnel, rubber band, thermometer, pH indicator or test strip, and food coloring.

You may be wondering: why the thermometer in the optional materials list? 

One of the three components to this activity is measuring the temperature change from the reaction. The other two are comparing the density of a CO2 filled balloon with the air around us, and measuring if there is a pH change when CO2 mixes with water. 


  1. Put ~1/2 c vinegar into the bottle 
  2. Measure and record the temperature of the vinegar. You can do this just by feel or by using a thermometer if you have one available. Do you think it will get warmer or colder after the reaction? 
  3. Spoon about 2 Tbs baking soda into the balloon (this is where the funnel is helpful)
  4. Place the balloon over the mouth of the bottle and secure it with the rubber band, as in the third picture.
  5. When ready, lift the balloon up and allow the baking soda to fall into the bottle and enjoy the reaction!

Question #1: how did the temperature change? After the fizz has died down a little, go ahead and feel the bottle or measure the liquid temperature. Did the result surprise you? 

Question #2: If you take off the balloon from the bottle and tie it off filled with CO2 gas from the reaction, and let it go in mid-air, will the balloon sink, float, or rise? 

Question #3: If you were to blow CO2 into water, how would that change the pH of the water? If you’re careful and talented, you could cut a small opening in the neck of the balloon while pinching it off, place it over a straw, then release the pinch and let the gas bubble into the water. Afterwards, you can measure the pH using an indicator, pH meter, or test strip. If you don’t want to deflate the balloon, given that humans exhale CO2, you can simply blow bubbles through a straw into water for about a minute to get a pH change without destroying your CO2 balloon. 

Answer #1:  The science behind this (source: American Chemical Society) is that every chemical reaction is accompanied by a change in temperature. Sometimes the change is barely noticeable and other times it’s extreme. Sometimes the temperature goes up and other times it goes down. In this reaction, Baking soda reacts with the vinegar to produce carbon dioxide gas, sodium acetate, and water. It took energy to break the baking soda and vinegar apart and energy was released when the carbon dioxide, sodium acetate, and water were formed. Since more energy was needed to break the baking soda and vinegar apart, the temperature went down. This reaction is called an endothermic reaction. 

Answer #2: The chemical equation for the reaction between baking soda (sodium bicarbonate) and vinegar (acetic acid), looks like: NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2. In English, the reaction produces CO2 gas, liquid water, and sodium acetate. The CO2 is what blows up the balloon and fills it. 

Answer #3: The baking soda and vinegar reaction is an acid/base reaction (vinegar=acetic acid). pH is a measurement of the hydrogen (H) in an aqueous, or water containing, solution. Measured on a scale of 0-14, acids are below a pH of 7, and bases are above, with 7 being neutral. What you should find is introducing CO2 into neutral water turns the water slightly acidic. For more information, look up “Ocean Acidificaion”. 

I hope you enjoyed this activity! Please feel free to provide any feedback or ask questions about these tests. 

Outdoor STEM, Day 1: Sundials

Paper Plate Sundial

  1. You’ll need to know where north is for this activity (an opportunity for a mini-lesson on the directions if your kids don’t know them yet!), a paper plate, and a pen and pencil. You’ll also need to find some sunshine! You may have to move the plate throughout the day to find the sun; just continue to keep it oriented north as described below. 
  2. Stick the pencil up through the middle of the plate
  3. Write “N” on the edge of the plate (see picture), then orient the “N” to face north. 
  4. Trace the pencil shadow on the plate, and write the time in the shadow. 
  5. Several times throughout the day, trace the new shadow from the pencil. I recommend every two hours or so. 
  6. As the day progresses, watch how the pencil shadow moves across the plate. 
  7. Once you’ve got at least 4 spread out markings, you should be able to tell approximate time for the rest of the week! 

Human Sundial

  1. All you need for this is a partner, some chalk, and an outside spot that will get sun the whole day. 
  2. Pick one spot to stand on (both of you will stand on the same spot, taking turns), and mark it with an “X”. 
  3. Several times throughout the day, take turns tracing each other’s shadow in chalk. I recommend every two-three hours. Make sure to write the time in the shadow so you know when each shadow was created. 
  4. At the end of the day, notice both the path of the shadows and how the length of the shadows changed throughout the day. What does this tell you about the sun’s position and angle?