Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 373 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the iron setting (c) the kind of juice (d) the same paper
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the iron setting (c) the kind of juice
3. 3.True or false: reading the message is a job a child can do. (a) True (b) False
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) skip washing (d) rub your eyes
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) a small bowl (d) lemon juice
6. 6.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) ironing the paper (d) letting the paper dry
7. 7.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
8. 8.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
9. 9.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
10. 10.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
11. 11.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a battery cell (d) a mirror
13. 13.True or false: letting the paper dry is a job a child can do. (a) True (b) False
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) turmeric powder
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
16. 16.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
18. 18.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
19. 19.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) letting the paper dry
20. 20.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) putting the iron away (d) ironing the paper
21. 21.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) writing the message
22. 22.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
23. 23.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
24. 24.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) cutting the lemon (d) plugging in the iron
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) turmeric powder (d) a mirror
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
27. 27.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
28. 28.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
29. 29.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
30. 30.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
31. 31.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) reading the message
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) lemon juice (d) a cotton bud
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) lemon juice (d) yeast
34. 34.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
36. 36.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
37. 37.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
39. 39.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) reading the message
40. 40.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a small bowl (d) a magnet

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