Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 452 · 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 same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
2. 2.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) reading the message
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a small bowl (d) a mirror
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) white paper (d) a mirror
5. 5.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) plugging in the iron (d) cutting the lemon
6. 6.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
8. 8.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
10. 10.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
11. 11.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
12. 12.True or false: putting the iron away is a job a child can do. (a) False (b) True
13. 13.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
14. 14.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
15. 15.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
16. 16.True or false: plugging in the iron is a job for an adult. (a) True (b) False
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a battery cell (c) an adult with an iron (d) white paper
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
19. 19.True or false: writing the message is a job for an adult. (a) False (b) True
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
21. 21.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) a balloon (d) yeast
22. 22.⚖️ 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) False (b) True
23. 23.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the same paper (d) the same cotton bud
26. 26.⚖️ 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 ironing time
27. 27.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
28. 28.⚖️ 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
29. 29.True or false: cutting the lemon is a job for an adult. (a) True (b) False
30. 30.True or false: ironing the paper is a job a child can do. (a) False (b) True
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) white paper (d) a balloon
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
33. 33.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
34. 34.⚖️ 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
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
37. 37.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) dipping the cotton bud (d) reading the message
39. 39.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) an adult with an iron (d) white paper

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