Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 392 · 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.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) reading the message (d) ironing the paper
2. 2.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
3. 3.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same paper (c) how dark the writing is (d) the same cotton bud
5. 5.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a battery cell
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it is sticky (d) it can burn skin
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
9. 9.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
10. 10.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
11. 11.True or false: plugging in the iron is a job for an adult. (a) True (b) False
12. 12.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
13. 13.True or false: ironing the paper is a job for an adult. (a) True (b) False
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
15. 15.⚖️ 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) how dark the writing is (c) the kind of juice (d) the same paper
16. 16.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) white paper (d) turmeric powder
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) yeast (d) white paper
19. 19.🛟 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
20. 20.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
21. 21.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) ironing the paper
22. 22.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) reading the message
23. 23.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) dipping the cotton bud (d) reading the message
24. 24.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
26. 26.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
27. 27.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) letting the paper dry
28. 28.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
29. 29.⚖️ 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
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a battery cell (d) a small bowl
32. 32.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) a magnet (d) an adult with an iron
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
35. 35.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
36. 36.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) putting the iron away
37. 37.🍋 Which of these steps is a job a child can do? (a) writing the message (b) putting the iron away (c) ironing the paper (d) cutting the lemon
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) putting the iron away
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False

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