Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 134 · 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.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a small bowl (d) a cotton bud
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
5. 5.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
6. 6.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) writing the message (d) reading the message
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
8. 8.True or false: yeast is needed for the secret lemon message. (a) True (b) False
9. 9.⚖️ 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) True (b) False
10. 10.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
11. 11.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) yeast
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
14. 14.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) ironing the paper (d) reading the message
15. 15.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) cutting the lemon
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the ironing time (d) the iron setting
17. 17.⚖️ 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 paper
18. 18.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) plugging in the iron (d) putting the iron away
19. 19.⚖️ 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 change it (c) we measure it
20. 20.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) plugging in the iron (c) ironing the paper (d) putting the iron away
21. 21.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
22. 22.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
23. 23.True or false: reading the message is a job a child can do. (a) True (b) False
24. 24.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
26. 26.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
28. 28.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
29. 29.🔮 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
30. 30.True or false: writing the message is a job for an adult. (a) False (b) True
31. 31.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
32. 32.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) reading the message (d) plugging in the iron
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a battery cell (d) a balloon
34. 34.True or false: plugging in the iron is a job a child can do. (a) False (b) True
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
36. 36.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
37. 37.🧺 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) a balloon
38. 38.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) reading the message (d) cutting the lemon
39. 39.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
40. 40.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky

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