Atlatl and Experimental Archaeology

(adapted from https://www.uwlax.edu/mvac/educators/lessons–activities/)

This lesson is designed to guide afterschool learners through the process of testing their hypotheses by performing experimental archaeology. An example of this process will involve atlatl throwing.

Grade Level: 6-8

Objective: The goal of the activity is for learners to learn about the physics of a projectile and engage in hypothesis testing by experimenting with an atlatl, or spear thrower.

Learning Outcomes: At the end of the lesson, learners will be able to explain levers and Newton’s Laws of Motion as they relate to the atlatl. Learners will also know how to make a hypothesis and test it.

STEM: math, technology, physics, and biology

Materials: atlatl, darts (different lengths if possible), target, tape measure, recording forms, pencils; atlatls and darts can be purchased online (e.g., https://www.thunderbirdatlatl.com/ or you can make your own [http://www.svcalt.mt.gov/education/textbook/Chapter2/Atlatl_LessonPlan.pdf; other lesson plans can be found online]).

Time: 60 minutes

Overview: An atlatl, or spear thrower is a stick or short pole with a wood or bone hook on one end. The end of the spear is inserted into the hook on the atlatl and thrown. The use of an atlatl allows the spear to go farther and with more force than if thrown only by hand.

Atlatls use leverage for greater velocity. The user is able to store energy during the throw. Atlatls often have a shaft with a peg at the end that supports the end of the dart and helps it to be thrown. The atlatl is held in one hand, farthest from the hook end and the dart is thrown adjacent to the ear. The person’s arm with the atlatl acts as a lever. The atlatl extends the throwing arm, increasing the length of the lever and allowing more force from the arm through the spear holder to the dart, which means more energy and greater speed (over 150 km/h ([93 mph]). This is the same as using a “Chuck-It” for throwing dog balls. The use of spear throwers is very old (ca. 30,000 years) and seen in several parts of the world. The earliest known example is a 17,500-year-old Solutrean reindeer antler atlatl from Combe Saunière (Dordogne), France. The bones of an individual dating to 42,000 BP have arthritis in the right elbow, called “atlatl elbow,” developed from atlatl throwing. There is no evidence for atlatls in Africa. Atlatls were used throughout the Americas, from the earliest arrival of people. Most people in Europe stopped using atlatls and switched to bow and arrow around 10,000 years ago. In North America, people did not use bow and arrow until around 1500-1000 years ago.

NEWTON’S LAWS OF MOTION

Newton’s first law: Every object in motion tends to remain in motion unless an external force is applied to it. The same applies to an object at rest.

An object at rest will remain at rest and an object in motion will remain in motion unless something happens to them (e.g., friction or air resistance).

Newton’s second law: F = ma: This is the relationship between an object’s mass (m), its acceleration (a), and the force applied to it (F).

Force is directly proportional to acceleration, so if I increase the force on an object then I will increase its acceleration, and if I decrease the force on an object then I will decrease its acceleration.

Force is also directly proportional to the mass of the object, so if I have a larger mass then I must apply a larger force to get the same acceleration.

Mass is indirectly proportional to acceleration, so if I have a larger mass its acceleration will be less than that of a smaller mass object using the same force to cause the acceleration.

Simply put: Heavier and faster equals more force

Newton’s Third Law: For every action there is an equal and opposite reaction.

Every time you have a movement or a push in one direction there is the same amount of movement or push in the opposite direction.

Atlatls are a third-class lever system (the extension of the forearm [the forward throwing motion] uses the elbow as the fulcrum)

Third class = pivot – force – resistance

Examples: tweezers, tongs (with the hinge at one end), chopsticks, stapler remover, shovel, broom, bottle opener

The extension of the forearm (the forward throwing motion) uses the elbow as the pivot point; the triceps muscle is the force and it is attached to the forearm a short distance further on the forearm; the resistance is the object held in the hand furthest out from the pivot.

The flick of the wrist at the end of the throwing motion is also a third class lever system.

The triceps produce the force with very little motion and the end of the atlatl moves over a great distance thrusting the spear forward with great momentum.

When you throw something like a dart, you use your arm muscles to accelerate your hand and the thing you are throwing. As you throw, your hand pushes on the object as you throw it, speeding it up, and giving it more energy. Once the object leaves your hand, you can’t push it anymore, so you can’t give it any more energy than it had when it left your hand.

The atlatl acts like an extension of your arm, it makes your arm longer and gives you an extra joint. This way you can continue to push the dart after it has moved beyond the reach of your hand. Figure 1 shows five snapshots of the process of throwing a dart by hand. Figure 2 shows seven snap shots of the process of throwing one with an atlatl. The first four frames of both figures are very similar, but in the fifth frame of Figure 1 the dart has been released, and is no longer speeding up. In frame five of Figure 2, the dart is out of reach of the hand, but not of the atlatl, so it is still gaining energy. It is not until the seventh frame that the dart is released, by which point it has gained significantly more energy.

Vocabulary: scientific method, hypothesis, atlatl, darts, atlatl weight, Newton’s Laws of Motion, lever, experimental archaeology

Procedure: Tell learners we will be conducting experimental archaeology. In experimental archaeology, people make and use the same things that were made and used in the past (an arrowhead, a longhouse, a clay pot). Discuss what an atlatl is (Show video clips [https://www.youtube.com/watch?v=Ej3it7Ct76w]). Ask learners why they think it was used.

Ask learners if they have ever used a Chuck-It. If so, ask them why. Explain that an atlatl and a Chuck-It are the same – both simple machines.

Briefly go over Newton’s Laws of Motion as they relate to the atlatl.

Ask learners to identify the levers used in simple machines. Demonstrate with a video (e.g., https://www.youtube.com/watch?v=VQjaIvx5iRM).

Ask what is an example of a lever in your body? A lever is a rigid object that makes it easier to move a large load a short distance or a small load a large distance. The forearm is a third class lever because the biceps pull on the forearm between the joint (fulcrum) and the ball (load).

In a large, open field, demonstrate throwing a dart without and with an atlatl. Measure how far learners can throw the dart with or without the atlatl, with spears of different lengths, their degree of accuracy, and, if possible, their success hitting moving versus stationary targets (see data collection sheet below).

Atlatl hunting and experimentation take place on a large scale today (e.g., World Atlatl Association) and learners can benefit from prior research and compare it to their own experiences.

Discuss the lesson on Newton’s Laws as learners are throwing the atlatl.

Discuss with learners how we will measure distances (show them the large tape measure). Ask them what unit of measurement we should use (inches, feet). Discuss why one unit is better to use in this experiment than another and how selecting the correct measurement is important in science. Ask them if they know the metric system. Tell them that is the standard for archaeology. Have them compare a foot and a meter.

Youth will report how (or if) they would change their hypothesis based on the experiment and data. They will make new hypotheses, retest them, and evaluate data again to support understanding of the scientific method. This can be done on Day 2 if not done on Day 1.

Extensions/alternatives: An alternative, if there is time, is to have learners go out and throw the atlatl, then come up with hypotheses, and then go back out to throw the atlatl and test their hypotheses.

Have learners calculate the difference between their best and worst (farthest and closest) throws with the atlatl; or calculate the difference between farthest distance thrown with vs. without the atlatl. What was the range of distances thrown by each individual and by the group as a whole? Have learners calculate the average distance thrown by all members of the group.

Assessment Activities: During the lesson, instructors will monitor youth to ensure they are all actively participating. Youth will fill out the form below. At the end of the lesson, youth will restate their hypothesis, present their data, and report whether their hypothesis was correct.

Wrap up: Class will end with a restatement of the learning outcomes. Ask youth: What worked for you? What did you use from the physics lesson when you were throwing? Was your hypothesis correct? Why or Why not? Was enough data obtained to support the hypothesis?

Crosscutting Concepts: Cause and Effect: Mechanism and Prediction: Events have causes, sometimes simple, sometimes multifaceted. Deciphering causal relationships, and the mechanisms by which they are mediated, is a major activity of science and engineering.

• Cause and effect relationships may be used to predict phenomena in natural or designed systems.

NYS Standards: MS. Forces and Interactions,
MS-PS2-1. Apply Newton’s Third Law to design a solution to a problem involving the motion of two colliding objects.* [Clarification Statement: Examples of practical problems could include the impact of collisions between two cars, between a car and stationary objects, and between a meteor and a space vehicle.] [Assessment Boundary: Assessment is limited to vertical or horizontal interactions in one dimension.]

MS-PS2-2. Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object. [Clarification Statement: Emphasis is on balanced (Newton’s First Law) and unbalanced forces in a system, qualitative comparisons of forces, mass and changes in motion (Newton’s Second Law), frame of reference, and specification of units.] [Assessment Boundary: Assessment is limited to forces and changes in motion in one-dimension in an inertial reference frame and to change in one variable at a time. Assessment does not include the use of trigonometry.]

Experimental Archaeology: Atlatl Throwing

Name:_________________________________________________________________Date:______________________

Experimental archaeology attempts to replicate past lifeways to better understand past human practices. For this exercise, we will use an atlatl, or spear thrower, to test the effectiveness of this technology.

Remember: SAFETY FIRST!