The small moments of everyday life present huge opportunities for learning about the world around us. Pouring a glass of milk is a learning opportunity. Start with a question to get the conversation rolling.
Why do we have to drink milk?
How is drinking milk good for you or what parts of you benefit from drinking milk?
How does milk compare to other foods that are supposed to be good for you?
Where does milk come from?
Do animals other than cows produce milk?
What other foods are made from milk or cream?
How are those foods made?
Observe + Compare
To start, look at, smell, taste and feel whole milk. Find the words to describe what it tastes like or looks like and feels like. Do the same with cream, buttermilk, skim milk, kefir, almond milk (though technically a different class), goat’s or sheep’s milk if you have access and want to pay for those.
Consider creating a graph rating various milk products in terms of thickness, the desirability of the taste, color, or any other quality that occurs to your child.
If you are a fan of cheese and willing to purchase different types, you can do the same set of observations and comparisons. Look for cheeses from cows, sheep, and goats. Examine colors, rinds, holes (if any), molds (if any), and texture (hard or gooey soft). Taste, feel and smell those different cheese or grated versions. How do they compare? Once again find the words to describe these sensations. Why is that some cheese that smells bad, will taste fantastic (or maybe this is an adult phenomenon).
Similar observational comparisons could be made across other dairy products or comparisons of yogurt, frozen yogurt, ice cream, butter (not margarine which is non-dairy), cottage cheese, sour cream, or my favorite, mascarpone.
Ask your child to list foods that are supposed to be “good for you.” Is milk on the list? Are other dairy products on the list? Does the list include things your child likes or foods that actually have some health benefit? Do you need to have a discussion about healthy foods?
So dairy products come from cows, sheep, or goats. “Milk” products are also available where the source is nuts or soy, or distinctly not mammals and for that matter, not technically milk. What other foods do we get from cows? If you eat beef, chances are you also occasionally eat pork. Why is it, however, that we do not drink pig’s milk which is apparently high in fat and nutrient rich? I guess the answer is that pigs are hard to milk.
Discuss the notion of volume of liquid dairy products, pouring amounts into measuring cups. Start with how much milk is in your child’s glass at dinnertime, or how much goes onto the cereal in the morning, measuring these amounts.
If you have a scale, weigh the cheese slices that go onto a sandwich or the chunk of cheese consumed for a snack. Take a bite out of that chunk and weigh it again.
Butter can be measured in tablespoons. This is easy as those measurements are typically on the side of the paper the stick of butter is wrapped in. Again if you have access to a scale, how much does a tablespoon or a stick of butter weigh?
If you have a balance scale, consider pouring a cup of milk into a glass. Next, pour a cup of buttermilk or cream into an identical glass. Place the two glasses on the balance scale. Does one weigh more than the other? How do skim and whole milk compare? How does goats’ milk and cows’ milk compare? If the same volumes of these liquids weigh different amounts, why? If you do not have a balance scale but access to a different scale, just take good notes so that you and your child can compare weights.
Invite your child to count how many glasses of milk he drinks in a day or a week. You can help him estimate approximately how many glasses he drinks in a year.
Examine recipes that include dairy products. How much cheese does a mac and cheese recipe call for? What does that amount look like, or how much would a cup or two of cheese look like? Discuss other recipes using milk, cream, buttermilk or yogurt. How much is used? What are your child’s favorite recipes? If you make recipes with cheese, vary the kind of cheese, or for example, use cheddar instead of Muenster or Gouda. Which is preferred? When melted, do different cheese all feel the same way?
Try mixing milk and Coca-cola. The phosphoric acid in the cola interacts with proteins in the milk causing them to precipitate out. The phosphoric acid molecules attach to the proteins making them dense or heavy. Interesting for thinking about protein in milk. The solid matter is milk curdled by the acid in the cola. The other liquids weigh less and accumulate above the solid.
Discussing the results of this experiment may also be a good way to convince kids that drinking too much Coke may not be healthy because of the effects of the acid on our teeth and bones, not to mention the amount of sugar.
Mix 4 teaspoons of vinegar with 1 ½ cups of skim milk. Microwave this combination for one minute. Heating this mixture will cause a chemical reaction separating the milk into two parts, or curds and whey. Strain the liquid (through a sieve or cheesecloth) and roll the solid into a blob in the palms of your hands once it is cooled. If left on its own it will harden. This is essentially cottage cheese, or once rolled together it is a cheese, but it won’t taste very good. Cheesemakers do not use vinegar. Rather they add an enzyme called rennet that causes the milk to curdle and results in a more appealing taste.
Fill a plate with whole milk. Place drops of food coloring on/in the milk. You can use one color or several, but you only need to place a drop in the milk. Spread these drops out so that they are not too close together. With one end of a clean cotton swab, touch the milk. What happens? Just touch the surface of the milk lightly. No need to swirl or stir the milk. Now put a little dish soap on the other end of the cotton swab. You can dab some on, or dip the tip of the cotton swab into some dish soap you have squirted out onto a separate plate. Touch the end of the cotton swab with soap on it on the surface of the milk. Now, what happens? Experiment touching different parts of the milk or the food coloring drops.
As we learned in the last activity post, soap has molecules with two ends. One end is attracted to water and the other end bonds with grease and dirt. Whole milk is mostly water, but also contains fat among other things such as proteins and minerals. In this case, the soap bonds with the fat in the milk. In fact, the soap molecules are moving around the solution trying to bond with all of the fat molecules. All this movement bumps the drops of food coloring resulting in the observable “color blasts.”
Here is an interesting comparison. Take a pint of heavy cream (whipping cream). Pour a little over half of it into a bowl and the remaining portion into a jar with a securely fitting top. Whip the cream in the bowl with an electric mixer. The end result will be whipped cream. Add sugar and vanilla and put a dollop on a dessert. Yum… Next, shake the remaining cream in the jar. The jar should be about half full. Shake, shake, shake!! You will have to keep shaking for 10 minutes or so. All this shaking could be hard for one person, so find some people to help, take turns and add some dance music or exercise moves. Ultimately you should see a glob appear. This is butter. Pour off the liquid and taste your butter, spreading on a piece of bread or cracker. How does it compare to the butter you buy? Add a little salt if you like.
So what happened? In both instances, you started with some cream. By treating it differently, either shaking or whipping, you ended up with two rather different results. By whipping the cream, you are adding air and increasing the volume of the cream and changing its texture. But the fat in the cream provides the structure for the air. By agitating or shaking the cream, the fat globules suspended in the liquid are shaken out of position and crash into one another and clumping together. They then separate out from as a semi-solid from the liquid. The remaining liquid is buttermilk.
Vary these experiments by using refrigerated versus room temperature milk or cream. Are there differences in the results? Weigh the cream before it is whipped or shaken. Now weigh the whipped cream and the butter/buttermilk. Are the before and after weights the same or different? Does adding salt or sugar change the results?
Make some ice cream. This is another example of turning a liquid, or cream, into a solid by freezing it.
Explore different recipes using cheese, sour cream, cottage cheese, yogurt or any dairy product. Keep track of your favorites.
What other animals drink milk?
Visit a dairy farm or find a book to learn how cows are cared for and milked. What do cows eat? Are there different kinds of cows, or why are some brown and white and others are black and white, or black all over?
Visit a farm with sheep or goats that are milked or you may see this process at a county fair. You may also watch this on YouTube, https://www.youtube.com/watch?v=YQxErwDd2sg.
Explore the health benefits of milk. Babies less than one year have trouble digesting cows milk. Infants should be breastfed or consuming formula. For children between the ages of 1 and about 3, whole milk is preferred as it contains fat that is essential for brain development. After about 3 years of age, 1% or 2% milk is fine for kids.
Milk is good for bone development, but don’t forget that physical activity is also essential and maybe even more important! Milk remains a good source of calcium, Vitamin D, and protein; but not the only source.
Not everyone can drink milk and feel good. Some folks are lactose intolerant or allergic to the proteins in milk. Your child may already know other kids who have food allergies. This is another food that can be added to that list. Discuss substitutes such as soy, rice, almond, hemp or coconut milk.