Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 539 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) turmeric powder
2. 2.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
3. 3.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
4. 4.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
5. 5.True or false: ironing the paper is a job a child can do. (a) False (b) True
6. 6.True or false: writing the message is a job a child can do. (a) True (b) False
7. 7.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
8. 8.⚖️ 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) how dark the writing is (d) the kind of juice
9. 9.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
10. 10.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
11. 11.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
12. 12.True or false: reading the message is a job a child can do. (a) True (b) False
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) the same cotton bud (d) how dark the writing is
14. 14.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) an adult with an iron (d) a balloon
15. 15.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
16. 16.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
18. 18.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a small bowl (d) a magnet
21. 21.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same paper
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
25. 25.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
26. 26.True or false: letting the paper dry is a job for an adult. (a) False (b) True
27. 27.⚖️ 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
28. 28.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
29. 29.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
30. 30.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) plugging in the iron
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a balloon (d) a cotton bud
33. 33.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
34. 34.⚖️ 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) True (b) False
35. 35.⚖️ 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
36. 36.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
37. 37.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
39. 39.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
40. 40.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words

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