Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 57 · 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? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same paper (c) the same cotton bud (d) the kind of juice
4. 4.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a small bowl (d) turmeric powder
6. 6.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
7. 7.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
8. 8.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) reading the message (c) cutting the lemon (d) plugging in the iron
9. 9.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) reading the message (d) writing the message
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
11. 11.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
12. 12.True or false: putting the iron away is a job a child can do. (a) False (b) True
13. 13.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a mirror (c) yeast (d) a balloon
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a small bowl (d) an adult with an iron
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a mirror (c) yeast (d) a battery cell
16. 16.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
17. 17.True or false: plugging in the iron is a job a child can do. (a) False (b) True
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
19. 19.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
20. 20.True or false: cutting the lemon is a job a child can do. (a) False (b) True
21. 21.True or false: putting the iron away is a job for an adult. (a) True (b) False
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
23. 23.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
24. 24.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
25. 25.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
27. 27.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) plugging in the iron (d) letting the paper dry
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) a balloon
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) writing the message (d) reading the message
30. 30.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
31. 31.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) ironing the paper (d) writing the message
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) dipping the cotton bud
33. 33.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
34. 34.🛟 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
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
37. 37.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
38. 38.True or false: reading the message is a job a child can do. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
40. 40.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed

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