Lever, wheel and axle, pulley. 

 - Niles, IL :  United Learning,  1991. 
 -  1 videodisc (VCD) (11 min) : sd., col. ; 4 3/4 in. 
<br/><br/><br/>English 
<br/><br/><label>ISBN: </label>VCD 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Levers<br/>Wheels<br/>Pulleys<br/>Axles<br/>Simple machines
<br/><br/><label>LC Class. No.: </label>621.8 L57 c1991