Beacon Lesson Plan Library

Endothermic or Exothermic That Is the Question.

Jeri Martin


What happens to the heat energy during a chemical reaction? Students will become familiar with an endothermic reaction by testing a chemical reaction.


The student knows that a transfer of thermal energy occurs in chemical reactions.

The student uses appropriate procedures for safety in the classroom, home, and community.


(per group of 2 3 students)
- 250 mL beaker (1)
- Effervescent tablets (2 tablets = 1 package - tablets are Sodium Bicarbonate with citric acid)
- 100 mL water
- Celsius, red alcohol thermometer (1)
- Paper towels (1 per student)
- Stop watch (1)

(per student)
- Graph paper (1 piece)
- Colored pencils (1 blue and 1 red)
- Ruler (1)


1. Make copies of the K W L chart, Endothermic/Exothermic Rubrics and Endothermic or Exothermic Lab, one copy of each for each student.
2. Prepare equipment for lab activity.
3. Gather needed materials.
4. Checklist of items you may need to purchase:
_____ Effervescent tablets
_____ Paper towels


1. Give each student a copy of the Endothermic/Exothermic Rubrics. Discuss the rubrics with the students explaining, even though this lesson is concerned with endothermic and exothermic reactions, safefy procedures and proper use of lab equipment is expected. (See copy in Associated File)

2. Give each student a copy of the KWL chart for Endothermic or Exothermic. (See copy in Associated File).

3. Discuss with students the K (what do you know) and W (what do you want to know) from the chart. The L (what did you learn) will be completed at the end of this activity.

4. Have students perform the 'Endothermic or Exothermic Lab' providing guidance and help where needed.(See copy in Associated File).

5. Have students complete the L section of their K W L chart and submit for assessment.


The Endothermic/Exothermic rubric is marked as students go through this activity. The KWL chart and Endothermic or Exothermic Lab will be collected. The entire Endothermic/Exothermic Lab and L section of the KWL chart will be assessed. Offer feedback and guidance as you circulate and watch students work.


1. If students are having trouble with observations of chemical reactions, they can make additional observations by completing the following activity:

Purpose: Students will learn to make careful observations involving chemical reactions.
Materials Needed:
- Road salt (calcium chloride)
- Baking soda (sodium hydrogen carbonate)
- Indicator (phenol red or bromthymol blue work well)
- Baggies, sandwich size (regular and ziplock)
- Spatulas or plastic spoons
- 10 ml graduated cylinders

1. Put two scoops of road salt and one scoop of baking soda into a ziplock bag.
2. In another baggie (not ziplock) put 10 ml of indicator.
3. Place the baggie containing indicator inside the ziplock bag with salt and soda. Be sure the indicator baggie is completely stuffed into the ziplock bag.
4. Carefully squeeze all air out of the ziplock bag.
5. Zip the top of the ziplock bag.
6. Invert the bag so that all contents of both bags combine. Make observations.
7. Several evidences of a chemical reaction are very apparent (color change, gas produced, heat produced., etc.) Make a list of all the observations you can gather. These include mass changes (if any), color changes, temperature of materials, sounds, and any other change you may note. Make this list on your own paper.

2. The procedures could be modified to allow it to be used as a cooperative group activity for ESE/ESOL students or if there are not enough supplies for each student to have their own individual set.

Web Links

Exothermic and Endothermic Reactions

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