Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 283 · 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.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) a magnet (d) a mirror
4. 4.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
5. 5.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) an adult with an iron (d) white paper
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
9. 9.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
11. 11.🛟 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
12. 12.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
13. 13.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) dipping the cotton bud (d) writing the message
14. 14.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) plugging in the iron
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) an adult with an iron (d) yeast
16. 16.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) white paper (d) lemon juice
18. 18.⚖️ 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 same paper (d) the kind of juice
19. 19.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a small bowl (d) a magnet
20. 20.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
21. 21.True or false: putting the iron away is a job a child can do. (a) True (b) False
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
24. 24.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) reading the message (d) ironing the paper
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) an adult with an iron (d) turmeric powder
26. 26.True or false: white paper is needed for the secret lemon message. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) turmeric powder (d) a small bowl
29. 29.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a small bowl (d) a balloon
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
32. 32.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
33. 33.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) reading the message
34. 34.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
35. 35.True or false: reading the message is a job a child can do. (a) True (b) False
36. 36.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
37. 37.True or false: ironing the paper is a job a child can do. (a) False (b) True
38. 38.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
39. 39.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
40. 40.True or false: letting the paper dry is a job for an adult. (a) False (b) True

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