Dissolving sugar and salt 0 Overview Using this Resource Connecting to the Curriculum Marking Student Responses Further Resources This task is about critiquing a plan for an investigation. Question 1Change answer Dylan wanted to find out whether water with dissolved salt evaporated faster than water with dissolved sugar. Here is the plan he wrote for his investigation: Mix 3 teaspoons of salt in half a cup of warm water. When the salt is dissolved, pour the solution into a saucer and put it on the window sill. Mix 2 teaspoons of sugar in half a cup of warm water. When the sugar is dissolved put the cup on the window sill. Check the solutions at 2 p.m. every day. When all the water has evaporated from the containers the answer will be known! a) There are some problems with Dylan's plan which means that it is not a "fair test". Write down two of the problems. Dylan wanted to find out whether water with dissolved salt evaporated faster than water with dissolved sugar. Here is the plan he wrote for his investigation: Mix 3 teaspoons of salt in half a cup of warm water. When the salt is dissolved, pour the solution into a saucer and put it on the window sill. Mix 2 teaspoons of sugar in half a cup of warm water. When the sugar is dissolved put the cup on the window sill. Check the solutions at 2 p.m. every day. When all the water has evaporated from the containers the answer will be known! a) There are some problems with Dylan's plan which means that it is not a "fair test". Write down two of the problems. Question b) Should Dylan always check both solutions together? Yes No c) Give a reason for your answer. Task administration: This task can be completed with pencil and paper or online. Level: 3 Curriculum info: Science, Investigating in science, Material World Key Competencies: Thinking Keywords: changes, evaporation, fair testing, evaluation, critique Description of task: Students evaluate a fair test about whether salt or sugar solution dissolves faster. Curriculum Links: Science capabilities The capabilities focus is brought about by the conversations you have and the questions you ask. Capability: Critique evidence This resource provides opportunities to discuss making sure that the method is measuring what will answer the investigative question. Science capability: Critique evidence (TKI) Science capabilities: Critique evidence Answers/responses: Y5 (11/1996) Y6 (11/1996) a) Any 2 of: Different amounts of salt and sugar. Salt solution poured into saucer. Sugar solution left in cup. Only one trial. very difficult very difficult b) Yes moderate moderate c) Dylan is measuring time to see which one evaporates first – therefore he needs to check both at the same time. very difficult very difficult Other Level 3 ARB resources that have a fair testing focus: Baking soda and lemon juice Investigating crater impact Which paper soaks up most water? Viscosity of liquids Which parachute floats the longest? Bouncing soccer balls Dissolving milo Rolling marbles Rolling marbles II Rusting nails The best mopper upper Evaporating water
