Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 367 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
2. 2.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) dipping the cotton bud (c) ironing the paper (d) cutting the lemon
3. 3.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
4. 4.True or false: putting the iron away is a job for an adult. (a) False (b) True
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
6. 6.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
7. 7.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
8. 8.True or false: plugging in the iron is a job a child can do. (a) False (b) True
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) brown (d) green
10. 10.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
11. 11.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
12. 12.⚖️ 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) False (b) True
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a battery cell (c) white paper (d) a cotton bud
14. 14.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) letting the paper dry
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
16. 16.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) lemon juice (d) a balloon
17. 17.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) yeast (d) an adult with an iron
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
20. 20.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) ironing the paper (d) plugging in the iron
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
22. 22.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) cutting the lemon
23. 23.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) white paper (d) a battery cell
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) a small bowl (d) a cotton bud
26. 26.True or false: ironing the paper is a job a child can do. (a) True (b) False
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) turmeric powder (d) lemon juice
28. 28.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
29. 29.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
30. 30.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a cotton bud (d) a mirror
32. 32.⚖️ 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 kind of juice (c) how dark the writing is (d) the same paper
33. 33.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
34. 34.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) yeast (c) white paper (d) an adult with an iron
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) turmeric powder
37. 37.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) writing the message (d) ironing the paper
38. 38.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) cutting the lemon
39. 39.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) writing the message (d) dipping the cotton bud
40. 40.True or false: letting the paper dry is a job a child can do. (a) False (b) True

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