This unit comprises 4 stations which develop students' concept of, and "feel for", a gram. The stations may be taken as whole class activities or they may be set up as activities that groups of students use throughout the week.
When students can measure objects effectively using non-standard units, they are ready to move to the use of standard units. The motivation for moving to this stage often arises from experiences in which students have used different non-standard units for the same mass, and have subsequently realised that the use of consistent units allows for easier, and more accurate, communication of mass measures.
Students’ measurement experiences must enable them to:
It is sensible to begin with the kilogram as the gram is too small to "feel". An appreciation for the feel of a kilogram needs to be built up with lots of examples of 1 kilogram mass. For example, 1 kilogram bags of stones, polystyrene, sand, butter and nails. Students should compare a standard 1 kilogram mass with other objects, first by holding them, and then by using a balance scale.
The usual sequence is then to divide the kilogram into smaller parts, for example, ½ a kilogram (500 grams), ¼ of a kilogram (250 grams) and 1/10 of a kilogram (100 grams). If appropriate to the knowledge of your students, you might record these numbers and a relevant expression (e.g. 500 is 1/2 of 1000) alongside the measurement of different items.
Next, students should have opportunities to explore the size of the gram. This can be done by investigating the mass of very light objects, with 10g used as a starting point.
Metric measurements, and their position as a decimal system, lend themselves well to opportunities for revisiting and reinforcing ideas related to place value. E.g. If this object has a mass of 100g how many will it take to make 1000g or 1 kg?
The learning opportunities in this unit can be differentiated by providing or removing support to students and by varying the task requirements. Ways to support students include:
The context for this unit can be adapted to suit the interests and experiences of your students. For example:
Te reo Māori kupu such as ine (measure), grams, kilogram, and tatau (count) could be introduced in this unit and used throughout other mathematical learning.
You could also encourage students, who speak a language other than English at home, to share the words related to measurement that they use at home.
In this station we use the scales to measure and make Chocolate Bubble Cakes. We suggest that you carry out this station as a whole class (as it involves cooking over heat and the use of edible ingredients). Alternatively, this could be done in small groups if you have a lot of available adult or very responsible student helpers available. Print off the instructions below for each group. If you feel the food context is not appropriate for your classroom, you could make a different, non-food item (e.g. slime or play dough).
Ingredients for chocolate bubble cake
250 grams vegetable shortening
100 grams icing sugar
25 grams cocoa
100 grams rice bubbles
100 grams coconut
Method for making chocolate bubble cake
Whilst the cakes chill, discuss the process with the students:
Once the cakes have chilled, have students estimate the mass of one cake. Support them to weigh it. As a class, discuss the following questions:
In this station we use kitchen scales and 10 gram weights to figure out the mass of very light objects.
Ask the students to find objects in the class they think will weigh about 10 grams and compare these to the weights. Then they need to weigh the object on the kitchen scales and record the working done to get the answer. Students ready for extension could be asked to find, measure, and record different combinations of classroom objects that have a mass of 10g, 20g, 30g etc. (i.e. different multiples of 10).
In this station we use the "feel" of 10 grams to make some guesses about light objects. We are not allowed to use any measuring scales to help with our guesses.
Present students with a variety of light objects in different, closed containers (e.g. paper clips, counters, drawing pins, cm cubes). Make memo pad paper and pencils available to students. Pass around the objects, or arrange them in the middle of a class circle. Have students feel the objects, and write their name and an estimate of the mass of each object on a piece of paper. This task could be repeated throughout the week with different objects. At the end of the unit, have students reveal their guesses to a partner or group, and then reveal, as the teacher, the mass of each item.
Students ready for extension could investigate the following questions:
Present students with the 100 g, 500 g and 1 kg items. Tell them we would need 10 of an item weighing 10 grams to make the same mass as the 100 g item, and 100 of them to make the 1 kg item. You might explore this using diagrams, arrays, and/or expressions (e.g. 1 eraser = 10 g. 100 erasers = 1000 g or 1 kg).
Challenge students to find objects in the classroom that they estimate, when combined, have a mass of 100 g, 500 g, or 1 kg. Students should put them them into a Ziplock bag, and swap their bag with a partner. Together, pairs of students should weigh their bags and record the findings.
Dear family and whānau,
This week we have been investigating grams and discovering just how light 1 gram is (a paperclip is about 1 gram).
At home this week we want you to measure the mass of something your child eats or uses after school (e.g. a violin, a basketball, an apple) and compare the difference to 100 grams.
Printed from https://nzmaths.co.nz/resource/great-grams at 4:24am on the 28th April 2024