Where in the World is the Elephant?

Engage:

The teacher will present a pumpkin.  Each student will write down how many seeds they think are in the pumpkin.

Good!  Today we are going to be talking about estimation.  To estimate something means to give the best guess after considering all the information given in a problem.

How can you figure out how many seeds are in the pumpkin without taking them out and counting them?

Good, good.  Do you think that your guess will match up to the actual number of seeds in the pumpkin?

Why maybe not?

What if I asked you to give me an estimate of the number of seeds in the pumpkin?  Then what would you do?

Well, you would have to take a guess. 

Maybe, maybe not. 

Because the odds of you guessing the number of seeds correctly are probably pretty slim. 

I would give you a number closest to the real number of seeds in the pumpkin.  So, I would just guess how many seeds I think are in the pumpkin  

Explore:

Students will be put into groups of 3 or 4.  There will be two activities going on:  a scavenger hunt and a card game.  Each group will have to complete both activities. 

Activity (1):

Students will complete a measurement scavenger hunt. Give teams of students a list of measurements, and have them find things that are close to having those measurements. For example, a list might include:

* a container that holds about 100 milliliters

* something that weighs more than 5 kg but less than 10 kg

* Something that is between 4 and 5 meters long.

Then I will come by and have them test out their estimation. 

Activity (2):

Divide students into groups of two or three. Each player is to be dealt twelve cards. When the students get their cards, they arrange them into three hands: one of three cards, one of four cards, and one of five cards. They then lay their hands face down in front of them. When the hands have all been arranged and placed down, all players turn over their three - card hands. The students then find the average of the three cards. The players round their averages to the nearest whole number. Players will check their estimations at the end of the game. 

Take out your conversions chart and look it up. 

This is what we talked about in class yesterday. You need to decide if the number 4 is closer to 1 or 5 or if the number 16 is closer to 10 or 20.  Remember your rules for rounding and decide as a group what you think the “nearest whole number” would be in your cases. 

  Students ask: 

What if I don’t know how much a milliliter is or how heavy a kilogram is?

What do you mean by “nearest whole number”?

Explain:

Students will present their findings as I ask for answers from each activity. I will ask groups for their estimations and the actual answers to the scavenger hunt.  I will have students write this on the board so we can see how close their estimations were to the real thing.

I will have students read one of their hands of three cards. 

I will keep asking students questions similar to the ones I asked Pedro. 

Teacher Does

Activity (1) Questions:

What did you find for a container that holds about 100 milliliters?

What did you find for something that weighs more than 5 kg but less than 10 kg ?

What did you find for something that is between 4 and 5 meters long?

Activity (2) Questions:

Okay Pedro, what was the first hand of cards you drew?

Okay, so what did how did you estimate the average of those numbers? 

Why did you round 25 to 24?

Interesting.  Nice Strategy. 

Student Response(s)

Answers will depend on what teacher has in classroom or brings from home. 

Jack, 3, and a 9. And a Jack is the same as #11. 

Well, I said that 11 was closest to the #10 and that 9 was closest to 10, and that 3 was closet to 5.  When I added 10+10+5, I got 25 and so I rounded that to 24 and divided that by 3 to get an estimation average of 8. 

Because I knew I was going to be dividing by 3 and I can’t divide 25 without getting a remainder.  So, I thought about the numbers close to 25 that are multiples of 3 and came up with 24 and 27.  Obviously, 24 is closer to 25. 

Elaborate: 

I will project a map of the United States onto the overhead making sure that every student can clearly see the projected map of the US. 

Discuss student responses and then give correct answer. 

According to the scale for this map, one inch= 250 miles.  I want you to estimate how many inches you think are between Austin (I will put a dot on the map) and New York City (and I will put a dot on New York City). 

Now, that you all have wrote how many inches you think are between Austin and New York City, figure out how many miles that is.  What would you have to do to figure this out?

Correct.

Students will do this independently. 

You would need to multiply the number of inches that you estimated by 250 miles. 

  Evaluate:

The students will do part A of the worksheet then go home and do part B.