Today I will be introducing thermometers. Students have used thermometers in first grade to record the daily inside and outside temperature. I am hoping that using the thermometers today will be a review, but I am prepared to take the time to introduce thermometers again if the need arises during this warm up. Before I assess their prior knowledge of thermometers, I am going to begin by asking students if they know how cold ice is? Have they heard the phrase "cold as ice?" What might it mean?
I give each student a piece of ice to hold. I ask for words to describe the temperature of the ice. Next I ask them how long they think it would take for the ice to turn to water? (Children have seen ice melt before, but having a reference of time and temperature is more science inquiry based, than just watching it melt.)
I ask students if they think they can slow down the melting process? How might they do that without a freezer (i.e. here in the classroom). I let students make suggestions. I tell them that they will have about 10 minutes to design a way to keep the ice from melting, but first we should see how warm the room is.
I hand out thermometers and we discuss the 2 scales on the thermometer. I ask students if they can point to the scale on the thermometer. (I look at what they are pointing to). What does the scale tell us? (how warm or cold something is, the temperature, the degrees). I say, "the scales tell us the degree that something is. When we measure how long something is we use ? (inches) When we measure how hot or cold something is we use? (degrees). Can anyone tell me why there are 2 different sets of numbers on the thermometer? (I am looking at how many students volunteer to tell me that there are 2 different scales. I know that not every hand up guarantees a right answer, but it does suggest some awareness on the part of students.) I say, "there are several different scales to measure the same temperature. Here in our country we measure in degrees Fahrenheit. In Canada they use the Celsius scale so when we say it is 32 degrees F here and water freezes at 32, in Canada they would say it was zero degrees. It is the same as when we measure in inches, but we can also measure in centimeters.
To check understanding of using a thermometer I ask students to find the temperature on the thermometer (room temperature). I ask students to write the number in their math journal. I walk around to check the number to see who has an idea of how to read the thermometer. I ask for a volunteer to record it on the board. I explain that we may not all have the same number because we may have read the small lines differently, but we should all be within a few degrees of each other. I talk about how attending to precision is very important when we measured (MP6), but that our thermometers are small and we may see the red slightly differently because of our eyes. If we are real scientists we would have a better thermometer so we would be able to get the exact temperature.
Next I ask them to hold the thermometer on their piece of ice. What is the temperature of the ice? They record their answer in their journal and we record that on the board as well. (For now I just leave the temperatures posted, but later in the lesson we will use these in creating word problems.)
I know that going through the reading of the thermometer is time consuming, but it is important for students to learn to use math tools appropriately(MP5) and they can't do this if they don't have a chance to practice.
Students create their ice insulators out of recyclable materials. When everyone has created their insulator, I hand out the ice and we record the time that we first put the ice in the insulator.
Once students have secured their ice cube in their insulators, we record the time on the clock as a starting point. I want students to use the analog clock to determine the hour and minute of start time. I do tell students to go to the nearest 5 minute interval when reading the time. I hand out practice clocks to those who need the added support of the visual clock with the minutes written out. I ask each student to figure out the time and write it in his/her journal. I circulate around to make sure that students have recorded the time correct. We leave 2 ice cubes on the shelf without insulators. We check each every 5 minutes during the lesson and record what we see.
We record temperature of water from the faucet, and from our hands during the 5 minute intervals to give students additional experiences with reading a thermometer. For the water from the faucet, I give each table a cup of water from the faucet and ask them to put their thermometers in the cup and count backwards from 45 to zero (counting backwards whenever students get a chance is great practice for subtraction). When they reach zero they should remove their thermometer and read the temperature and record it in their journals.
For the hands, I tell students to rub their hand together while they count backwards from 60 to 20. When they reach 20 they should put the ball of the thermometer between their hands, count back the rest of the way from 20 to zero and then read and record the temperature. Hand Temperatures
At each 5 minute interval, I ring the bell and ask students to record what they are seeing in their ice insulators . They note if the ice is smaller, bigger, gone, etc. When the ice has melted they should look back at the clock and record the new ending time (again to the nearest 5 minutes as this is the expectation for second graders telling time 2MD.C.7). The numbers and information can be used in Part II of the lesson to formulate and solve comparison number stories.
As a closing today I ask each student to set their clock for the start time and then count the minutes as they move the minute hand to the stop time. I tell them that the number they reach is how long it took their ice to melt. I have them record the melting time in their math journals.