Second Grade Misconceptions
of Weight – If it’s bigger, it has to be heavier!
Accessing prior knowledge and building upon those
concepts is an important teaching/learning task. Teachers are constantly
assessing what students already know about a topic to recognize how to connect
new information with what the learner already knows - hopefully creating
meaning. Often, teachers run into student misconceptions or incorrect
preconceived ideas concerning a topic. It is important to direct students to
recognize the misconception, help students to replace the misconceptions with
new conceptions, allow students to develop scientific thinking skills (using
new conceptions to solve problems) and assist students in acquiring the
knowledge to change from novices to experts (Mayer 235).
A few weeks ago, our second grade math text presented the
topics of weight and capacity. It was difficult to relate these topics to
students’ prior knowledge as students had not had much experience with
measuring capacity and weight of objects (though most had weighed themselves on
a scale). One misconception many of my students displayed was the idea that if
an object was large, it would have to weigh a lot. Students also thought that
bigger items must weigh more than small items. The misconception at hand could
be rectified by explaining that an object’s weight depends upon its composition
and the force of gravity. The following lesson attempts to tackle this
misconception and assist students in the process of conceptual change.
Lesson: Ounces and Pounds
Grade: Second
Time Frame: One Class Period
Materials: Objects of various weights and sizes
Ounces and pounds weights
Balance scale
Smartboard
Websites: http://www.mathcats.com/explore/balance/balance.html
http://www.linkslearning.org/Kids/1_Math/2_Illustrated_Lessons/6_Weight_and_Capacity/index.html
Instructional Sequence:
1.
Teacher and students brainstorm the
word weight. Teacher and students make a list of items that weigh much and
items that weigh little.
2.
Teacher states objective: Today we
are going to discuss weight with ounces and pounds. You will discover how to
compare and weigh objects using a balance scale. You will also determine what
kinds of objects weigh much (using pounds) and which weigh little (using
ounces).
3.
The teacher directs attention to the
smartboard for the short interactive lesson on weight found at http://www.linkslearning.org/Kids/1_Math/2_Illustrated_Lessons/6_Weight_and_Capacity/index.html
4.
Teacher holds up an ounce and a
pound. Teacher asks students which one is probably heavier? Students comment.
5.
Students are then given the
opportunity to hold both the ounce and pound and feel the difference in weight
while returning to desks. The teacher then reviews using scales and balances
with the students from the previous lessons in the unit.
Task 1
6.
Students are placed in groups of
four and directed to a station in the room. There are four stations and each
one has two objects. In groups, students travel to each station and
predict/record which object (of the two) will weigh more.
7.
Students return to desks to check
predictions as a class whole. Teacher models comparing the weights of objects
with the balance while students check predictions.
8.
Students and teacher discuss
findings. The teacher asks students if they made any predictions that were not
correct. Students and teacher discuss objects that were challenging in predicting
weight and why these objects were difficult. Students and teacher then discuss
the list of objects made at the beginning of class. The teacher circles objects
from the light object list and the heavy object list that are similar in size.
Students and teacher discuss how some objects can be small and heavy at the
same time or large and light. Students and teacher discuss why this can happen
and what it means. Students and teacher discuss the properties of the objects
and what makes different objects heavy. Students and teacher also discuss the
force of gravity on objects.
Task 2
9.
Students are then challenged to
determine if items weigh more or less than one ounce or one pound by predicting
and checking. With new knowledge from the first task, Students visit stations
around the room to weigh objects using a balance. Students determine whether
objects are more or less than one ounce or pound. Students and teacher discuss
findings and whether anyone made inaccurate predictions.
10. Students return to smartboard to complete an interactive use of a
balance through the website: http://www.mathcats.com/explore/balance/balance.html.
The teacher and students discuss the difficulties in using a virtual balance.
11. Teacher concludes lesson and directs students to the independent
practice page. Students are allowed to use a balance for independent practice
as the teacher observes.
Analysis of Lesson
In this lesson, the students and teacher compare and
discuss objects of different weights and sizes. The students and teacher first
access prior knowledge by discussing what weight is and making a list of heavy
items and light items. Students are asked to use the predict-observe-explain
method to recognize a common misconception– if
the object is big, it must be heavy. In the lesson, students move from
station to station predicting which objects are heavier than others. When
checking predictions, some students find that they were incorrect in guessing
the heavier object. For example, students could think that a large teddy bear
weighs more than a dictionary. Students could think that a kickball and bowling
ball weigh the same because they are the same size. As the students and teacher
check predictions by using the balance, they discuss the incorrect predictions,
why those predictions were made and why they were wrong. This stage
(recognizing misconceptions) helps the student realize the misconception and
begin forming a new conception about the weight of objects.
Next, the students need to replace this misconception
with a new conception. The teacher and students need to delve deeper into why
the predictions were wrong and what they know about the objects (properties). During
task two, students perform nearly the same activity. Students are now comparing
objects to the ounce and pound weights. This task should prove more successful
as students take into consideration the composition of the objects and law of
gravity. Students were also allowed the opportunity to feel the heaviness of
both an ounce and pound.
Finally, students are challenged to use an interactive
balance on the smartboard. This is more difficult for students to determine
which would weigh more as the object is not concrete and able to be physically
lifted. Students need to access what they know about the objects and think
about the composition of each. With practice, these tasks can allow the
students to begin working toward a higher level of understanding. As students
learn to take the objects properties into consideration, it will be easier to
generate more accurate predictions and draw accurate conclusions.
This lesson attempts to use both discovery learning and
problem solving. Students are challenged to use the knowledge of balances and
weights to guess and check various problems. When students make an incorrect
prediction, the teacher uses guided discovery to discuss what went wrong and
help shape thoughts for future problems. Students are also presented with
problem solving instances such as, Which
is heavier, I kilogram of rocks or 1 kilogram of feathers? Most students
explain, “The rocks are heavier, of course!” Rocks are heavier than feathers
right? This question requires problem solving and thought. Not often do you
have a kilogram of feathers available, but if that is the case, students could
use the balance to measure the kilogram of rocks with the kilogram of feathers.
This problem requires students to use logical reasoning to determine and
explain an answer. Reading the problem carefully and using other examples
besides rocks and feathers help the student discover that one kilogram is equal
to one kilogram no matter what substance is being measured.
I enjoy including technology in my lessons and feel that
both websites are great resources for explaining weight and using a balance.
The fault lies in the lack of concrete objects to hold. It is hard to illustrate
the weight of objects through the computer screen. However, there is more
opportunity for a variety of objects through these resources. For example, you
can compare a dinosaur and an elephant or an ant and a donkey.
References:
Mayer, R.E. (2003). Learning
and Instruction.