Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 51 · 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.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
2. 2.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
3. 3.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the same paper (d) the same cotton bud
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
6. 6.True or false: plugging in the iron is a job for an adult. (a) True (b) False
7. 7.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) putting the iron away (d) reading the message
8. 8.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
9. 9.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
11. 11.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) an adult with an iron (d) a mirror
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a battery cell (d) a cotton bud
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a balloon (d) white paper
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) lemon juice (d) a cotton bud
16. 16.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
17. 17.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the iron setting (c) the kind of juice (d) how dark the writing is
19. 19.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
20. 20.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) putting the iron away (d) plugging in the iron
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a small bowl (d) a cotton bud
23. 23.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
24. 24.True or false: putting the iron away is a job a child can do. (a) False (b) True
25. 25.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) reading the message
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
27. 27.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a cotton bud (d) turmeric powder
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) lemon juice (d) turmeric powder
29. 29.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a battery cell (d) yeast
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) yeast (d) white paper
31. 31.⚖️ 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
32. 32.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) lemon juice (d) turmeric powder
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) lemon juice (d) an adult with an iron
35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) cutting the lemon (d) writing the message
36. 36.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
37. 37.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
38. 38.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
39. 39.True or false: white paper is needed for the secret lemon message. (a) False (b) True
40. 40.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown

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